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X Brazilian School of Superconductivity (EBS 2012) –
IV Workshop on Frontiers of superconductivity and Magnetism –
Materials, Mechanisms and Applications (WFSM 2012)
10 -15 December, 2012
Olinda – PE –Brazil
SCIENTIFIC PROGRAMME AND ABSTRACT
Supported by:
ReNE/MCT

Organization
Conference Chairman
Prof. J. Albino Aguiar
Conference Secretary
Dr. Luis De Los Santos Valladares
Organizing Committee
J. Albino Aguiar
Antônio Jefferson da Silva Machado (EEL-USP)
Carlos Alberto Moreira dos Santos (EEL-USP)
Scientific Committee
José Albino Oliveira de Aguiar (UFPE)
Antônio Jefferson da Silva Machado (EEL-USP)
Carlos Alberto Moreira dos Santos (EEL-USP)
Clécio Clemente de Souza Silva (UFPE)
Ernesto Carneiro P. Raposo (UFPE)
Mauro Melchíades Dória (UFRJ)
Leonardo Ribeiro Eulálio Cabral (UFPE)
Edson Sardella (UNESP)
Conference webpage
http://blogs.df.ufpe.br/~EBS2012/
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Welcome Addresses
On behalf of the organizing committee it is my pleasure to welcome you to the X
Brazilian School of Superconductivity – IV Workshop on Frontiers of
superconductivity and Magnetism, Mechanisms and Applications (WFSM).
The main focus of the workshop is on Superconductivity at the Nanoscale, the
interplay between Superconductivity and Magnetism, Multiband
Superconductivity, Nano-engineered Pinning Arrays, Nanoscale Imaging,
Vortices in Mesoscopic Superconductors, Superconductor/Ferromagnet Hybrids,
High Tc cuprates, MgB 2 and Ferropnictides, Vortex Dynamics, Driven Vortex
Lattices, Ratchets, Nanoscale Fluxonics and related applications.
We hope that by jointing so many experts in the field and young scientists we
create a very exciting and stimulating environment that will booster new ideas
and collaborations. We wish a pleasant and productive stay at the beautiful and
World Heritage city of Olinda.
December, 2012.
J. Albino Aguiar
Chairman
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Programme
8.00
8.45
08:45 -
9:00
09:00 -
10:30
10:30 -
11:00
11:00 -
12:30
12:30 -
14:30
14:30 -
16:00
16:00 -
16:30
16:30 -
18:00
18:00 –
18.45
19:30 –
20:00
20:00 –
22:00
Monday 10/12 Tuesday 11/12
On site
registration
Wednesday
12/12
Thursday
13/12
Friday
14/12
Oppening - - - -
Minicourse I
Minicourse II
Minicourse III
Minicourse IV
Minicourse V
Minicourse VI
Minicourse VII
Minicourse VIII
Minicourse IX
Minicourse X
Kusmartsev
/Sardella
Passos/ Sotelo
Vasconcelos/
Apolinario
- Rezende
Cabral/
Romaguera
Break /Coffee
Oliveira/
Bustamante
Lunch
Govea/ Mauricio/
Renosto/
Cigarroa
Break / Coffee
Posters
Van de Vodel/
Xing
Peeters/
Chaves
Rustem/ Leao
Elmassalami/
Corredor
Maple/
Bud’ko
- - -
- - -
Fisk
Conference
Dinner
Doria/ Marino
Navau/ Crisan
Milosevic/ De
Souza Silva
Cohn/ Neumeier
Closing
Ceremony
Saturday
15/12
Departure
Minicourses:
Minicourse I - Fábio Dias
Minicourse II – Edson Sardella
Minicourse III – Angel Bustamante
Minicourse IV – Sergey Bud´ko
Minicourse V – Rustem Khasanov
Minicourse VI – John Neumeier
Minicourse VII – Joshua Cohn
Minicourse VIII – Adrian Crisan
Minicourse IX – Antônio Jefferson S. Machado Minicourse X –Juscelino Leão
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Chairs Schedule
09:00 -
10:30
10:30 -
11:00
11:00 -
12:30
12:30 -
14:30
14:30 -
16:00
16:00 -
16:30
16:30 -
18:00
18:00 –
18.45
Monday 10/12 Tuesday 11/12
Wednesday
12/12
Thursday
13/12
Friday
14/12
Machado Dias Oliveira Doria Milosevic
Break /Coffee
Passos Peeters Romaguera Cohn Xing
Lunch
Leao Sardella Corredor Gouvea Apolinario
Break / Coffee
Xing Elmassalami Landínez Téllez Jardim De Souza Silva
- J. Albino Aguiar Neumeier Machado
iv

Talks
Monday 10th
____________________________________________________________
Minicourses I-II
Minicourses V-VI
Chair: Machado
Chair: Leao
09:00‐09:45
Magnetic characterization of
superconducting materials (Fábio T.
Dias)
09:45 – 10:30
Solução numérica das equações de
Ginzburg-Landau pelo método de
variáveis de ligação (Edson Sardella)
Minicourses III-IV
Chair: Passos
11:00 – 11:45
Mössbauer spectroscopy for materials
science: The aging effect in the
superconductor
CaLaBa{Cu 1−x Fe x } 3 O 7−δ with 0≤ x
≤0.07. (Angel Bustamante)
11:45 – 12:30
Some remarks on synthesis, structural
characterization and measurements of
the physical properties of
superconducting pnictides (Sergey L.
Bud’ko)
14:30 – 15:15
Introduction to muon spin rotation and
relaxation (Rustem Khasanov)
15:15 – 16:00
Measuring the thermal expansion of
solids: How is it done, and how can it
be used to study phase transitions?
(John J. Neumeier)
Minicourses VII-VIII
Chair: Xing
16:30 – 17:15
Introduction to thermoelectric
properties of solids (Joshua L. Cohn)
17:15 – 18:00
Flux pinning in HTc superconductors
(Adrian Crisan).
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Tuesday 11th
____________________________________________________________
Minicourses IX-X
Chair: Dias
09:00‐09:45
Técnicas de síntese de materiais
supercondutores cerâmicos e
intermetálicos. (Antonio Jefferson da
Silva Machado).
09:45 – 10:30
From your laboratory to publishable
neutron data. Obtaining high quality
results (Juscelino B. Leão).
Oral
Chair:Peeters
11:00 – 11:45
Time reversal symmetry breaking and
the unusual magnetic order in
pseudogap state (Mauro Melchiades
Doria).
11:45 – 12:30
Magnetic field profile of a mesoscopic
superconducting SQUID: a study by
using Ginzburg-Landau theory (Edson
Sardella).
Limitation of ac electrical current by
SmBa 2 Cu 3 O 7-d ceramic (C. A. C.
Passos)
15:15 – 16:00
MagLev-Cobra: A Brazilian
Magnetically Levitated Vehicle
(Guilherme Gonçalves Sotelo).
Oral
Chair:Elmassalami
16:30 – 17:15
Multicanonical
distribution:
applications to flux avalanches in
superconductors (Giovani L.
Vasconcelos)
17:15 – 18:00
Madelung Energy of Regular Lattices
(S. W. S. Apolinario).
Oral
Chair:J. Albino Aguiar
18:00 – 18:45
Spin current phenomena: new impetus to
Spintronics (Sergio Machado Rezende)
Oral
Chair: Sardella
14:30 – 15:15
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Wednesday 12th
____________________________________________________________
Oral
Chair: Oliveira
09:00‐09:45
Vortex-antivortex configurations in thin
superconducting disks with an out-plane
magnetic dipole (Leonardo R. E.
Cabral).
09:45 – 10:30
Stabilizing composite vortex states in
hollow cylinders (Antonio R. de C.
Romaguera)
Oral
Chair:Romaguera
11:00 – 11:45
Penetration of magnetic field in type II
superconductors studied by time
dependent Ginzburg-Landau equation
(Isaias G. de Oliveira).
11:45 – 12:30
Study of the phase formation on
YBa 2 Cu 3 O 7-x coatings after sintering at
different temperatures (A. Bustamante
D.).
Oral
Chair: Corredor
15:15 – 15:30
Synthesis and superconducting
properties on the Ta-Zr-B system
(Custodio Ramalho M).
15:30 – 15.45
Possibility of unconventional behavior
in a new superconductor material of Zr 1-
xV x B 2 compounds (S.T. Renosto).
15:45 – 16.00
Superconductivity of a new noncentrosymmetrical
material of YCoC 2
composition (Cigarroa O.V).
16:30 – 18:00
POSTERS
Oral
Chair:Landínez Tellez
Oral
Chair:Neumeier
18:00 – 18:20
Local mapping of dissipative vortex
motion (J. Van de Vondel).
18:20 – 18:45
Effect of interface roughness on the
superconducting transition temperature
of Nb/Co multi-layers (Y. T. Xing).
14:30 – 15:15
Electric field-assisted consolidation of
(Bi,Pb) 2 Sr 2 Ca 2 Cu 3 O 10+y ceramic
samples (E. Govea-Alcaide).
3

Thursday 13th
____________________________________________________________
Oral
Chair: Doría
09:00‐09:45
Magnetoresistance oscillations in
mesoscopic superconductors (Francois
Peeters).
09:45 – 10:30
Inter-band interactions between vortices
in multi-band superconductors (A.
Chaves).
Oral
Chair:Cohn
11:00 – 11:45
Introduction to muon spin rotation and
relaxation (Rustem Khasanov).
11:45 – 12:30
Research possibilities at the NIST
Center for Neutron Research (Juscelino
B. Leão).
Oral
Chair:Jardim
16:30 – 17:15
Emergence of superconductivity from
magnetic order in correlated electron
materials (M. Brian Maple).
17:15 – 18:00
Fine tuning of the ground state of
CaFe 2 As 2 : Pressure, doping, and
nanoscale precipitates (Sergey L.
Bud’ko).
Oral
Chair:Machado
18:00 – 18:45
Superconductivity and Quantum
Criticality in Heavy Fermions (Z. Fisk).
Oral
Chair: Gouvea
14:30 – 15:15
The evolution of superconductivity in
the ternary AnM3n-1B2n (n=1:A= Ca,
Sr; M=Rh, Ir and n=3:A= Ca, Sr;
M=Rh) phases (M. ElMassalami).
15:15 – 16:00
Magnetic and Superconductor
properties of RuSr2GdCu2O8 -type
Ruthenocuprates (L.T. Corredor).
4

Friday 14th
____________________________________________________________
Oral
Chair: Milosevic
09:00‐09:45
Field induced superconductivity, dipolar
clusters and ferroelectricity in high Tc
superconductors (F. V. Kusmartsev).
09:45 – 10:30
From superconductivity to the Higgs
Boson (Eduardo C. Marino).
Oral
Chair:Xing
11:00 – 11:45
Magnetic cloaking and concentration
with ferromagnetic-superconducting
hybrids (Carles Navau).
15:15 – 16:00
Stabilizing fractional vortex states in
two-band superconductors with
mesoscopic magnetic textures (Clécio
C.de Souza Silva).
Oral
Chair:De Souza Silva
16:30 – 17:15
Unusual thermoelectric properties of the
quasi-one-dimensional metal,
Li 0:9 Mo 6 O 17 (Joshua L. Cohn).
17:15 – 18:00
A structural phase transition in V, Nb
and Ta and the possible importance for
A15 superconductors (John J.
Neumeier).
11:45 – 12:30
Investigation of the nature of artificial
pinning centres in nanostructured
superconducting films in correlation
with the bulk pinning force (Adrian
Crisan).
18:00 – 18:15
Concluding remarks (J. Albino Aguiar).
Oral
Chair: Apolinario
14:30 – 15:15
Flux fractionalization and flux
dynamics in two-band superconductors
(M.V. Milošević).
5

POSTER PRESENTATION
01 – Superconducting BSCCO pellets and wires prepared with nanoparticulated calcium
compounds
Natacha A. Nogueira, Dayse I. dos Santos
Grupo Mav/LMSCN – Pós Graduação em Ciência dos Materiais, Universidade Estadual Paulista,
Campus de Bauru, Brazil
02 - Processing and characterization of melt-textured Y 1-x Pr x Ba 2 Cu 3 O 7-d and [YBa 2 Cu 3 O 7-d ] 1-
x[PrBa 2 Cu 3 O 7-d ] x superconductor.
Yuri Aparecido Opata, Lincoln Bru, Leite Gusmao Pinheiro, Joao Frederico Haas Leandro
Monteiro, Simone Aparecida Silva, Pedro Rodrigues Jr., Alcione Roberto Jurelo.
Universidade Estadual de Ponta Grossa (UEPG), Campus Uvaranas, Av. General Carlos
Cavalcanti, 4748 – CEP 84030-900, Paraná, Brazil.
03 Fluctuation-induced conductivity and phase separation in composite samples (YBa 2 Cu 3 O 7-
d) 1-y (PrBa 2 Cu 3 O 7-d ) y
João Frederico Haas Leandro Monteiro, Yuri Aparecido Opata, Simone Aparecida da Silva,
Pedro Rodrigues Júnior, Alcione Roberto Jurelo.
Universidade Estadual de Ponta Grossa - UEPG, Rua Professor Cardoso Fontes 1100,
Condominio Arvoredo casa 06, Paraná, Brazil.
04 - London Approximation in a Nematic – Superconductor State.
Rafael de Vasconcellos Clarim, Daniel G. Barci
Universidade do Estado do Rio de Janeiro, Rua São Francisco Xavier 524, Maracanã, Rio de
Janeiro-RJ, Brazil.
05 - Effect of oxygen-content on the tribo-mechanical properties of single crystals YBa 2 Cu 3 O 7-
d superconductor.
Simone Aparecida da Silva, Alcione Roberto Jurelo, Carlos Eugênio Foerster, Francisco Carlos
Serbena, Gelson Biscaia de Souza.
Departamento de Física, Universidade Estadual de Ponta Grossa, Av. Gen. Carlos Cavalcanti
4748, 84.030-000, Ponta Grossa, Paraná, Brazil.
06 - Processing and characterization of YBa 2 Cu 3 O 7-x thick films using electrodeposition.
Thiago Luis Schneider, Pedro Rodrigues Jr., Jarem Raul Garcia.
Departamento de Física and Departamento de Química, Universidade Estadual de Ponta
Grossa, Ponta Grossa, Paraná, Brazil.
6

07 - Single crystal growth and characterization of the intermetallic systems YIn 3 and FeGa 3
Michael Cabrera-Baez, E.T. Magnavita, R.A. Ribeiro, L.M. Ferreira, C. Rettori, M.A. Avila.
Universidade Federal do ABC, Rua Santa Adélia 166, Barrio Bangu, Santo André, São Paulo,
Brazil.
08 - Superconductivity in the T 2 phase of the Ta 5 Ge 3-x B x
Lucas Eduardo Correa, Z. Fisk, A.J.S. Machado, C.A. Nunes, A.A.A. Pinto, G.C. Coelho.
Escola de Engenharia de Lorena, Universidade de São Paulo, P.O Box 116, Lorena, São Paulo,
Brazil.
09 - Synthesis and properties of a new superconducting compound of ZrNi x S 2 composition.
Arthur Carvalho Scaramussa, Z. Fisk, A.J.S Machado.
Escola de Engenharia de Lorena, Universidade e São Paulo, P.O. Box 116, Lorena, São Paulo,
Brazil.
Departments of Physics and Astronomy, University of California at Irvine, CA 92697, USA
10 - Superconductivity in a new compound of ZrCu x Te 2 stoichiometry.
Naiara Pasqualotti Baptista, T. Grant, S.T. Renosto, Z. Fisk, A.J.S. Machado.
Escola de Engenharia de Lorena, Universidade de São Paulo, P.O. Box 116, Lorena, São Paulo,
Brazil.
Departments of Physics and Astronomy, University of California at Irvine, Irvine, CA 92697,
USA.
11 – Vortex-Vortex interaction in two component Bose-Einstein condensates.
Davi Soares Dantas, A.R.P. Lima, Andrey Chaves, G.A. Farias, M. Milosevic, F.M. Peeters.
Departamento de Física, Universidade Federal do Ceará, Caixa Postal 6030, Campus do Pici,
60455-900, Fortaleza, Ceará, Brazil.
Department of Physics, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp,
Belgium.
12 - Dual view of the kinetic energy of superconductors.
Edinardo Ivison Batista Rodrigues, A.R. de C. Romaguera, M.M. Doria, A.A. Vargas-Paredes.
Universidade Federal Rural de Pernambuco, Rua Rui Duarte No. 153, Várzea, Recife PE, Brazil.
Departamento de Física dos Sólidos, Universidade Federal do Rio de Janeiro, Cidade
Universitária, Ilha do Fundão CP 21941, Rio de Janeiro, Brazil.
13 - Ginzburg-Landau theory to the two bands mesoscopic.
Karciano José Santos Silva, Antonio R. de C. Romaguera.
Universidade Federal Rural de Pernambuco, Departamento de Física, Av. Dom Manoel de
Medeiros s/n, Dois Irmãos, CEP 52171-900, Recife PE, Brazil.
7

14 - Structural, microstructural, magnetic and electrical characterization of ferromagnetic /
superconducting hybrid systems.
Daniela Rodrigues Borba Valadão, F.S. Portela, L.T. Corredor, E. Padrón-Hernández, Petrucio
Barrozo, J. Albino Aguiar.
Universidade Federal de Pernambuco, Rua Estevão de Sá, 390, Várzea, Recife, Pernambuco,
Brazil.
Departamento de Física, Universidade Federal de Sergipe, 49032-150, São Cristovão-SE, Brazil.
15 - Preparation and characterization of Fe 3 O 4 -Fe 2 O 3 /graphene oxide composite.
Blanca Azucena Gómez Rodríguez, Ricardo Batista, L. de los Santos Valladares, L.T. Corredor, J.
Albino Aguiar.
Universidade Federal de Pernambuco, Av. Prof. Moraes Rego 1235, Cidade Universitária,
Recife PE, CEP: 50670-901, Brazil.
16 - Crossover between BCS superconductor and BEC states in attractive Anderson lattice
model.
Daniel Reyes Lopez, Mucio A. Continentino.
Departamento de Física Teórica, Universidade do Estado do Rio de Janeiro, Rua São Francisco
Xavier 524, 20550-013, Rio de Janeiro, Brazil.
17 - Effect of Dy dopping on the structural, microstructural and magnetic properties of
ruthenium pyrochlores Gd 2-x Dy x Ru 2 O 7 .
Maria Danielle Rodrigues Marques, A.M. Silva, J. Albino Aguiar.
Programa de Pós-Graduação em Ciência de Materiais, Universidade Federal de Pernambuco
50670-901, Recife PE, Brazil.
18 - Magnetic studies of hematite hollow sub-micron spheres.
Silvia Marisel Espinoza Suárez, A. Bustamante, L. de los Santos Valladares, L. León, J. Albino
Aguiar.
TECSUP, Av. Cascanueces 2221, Santa Anita, Lima 43, Peru.
Laboratorio de Cerámicos y Nanomateriales, Facultad de Ciencias Físicas, Universidad Nacional
Mayor de San Marcos, Ap. Postal 14-0149, Lima, Peru.
Laboratório de Superconductividade e Materiais Avançados, Departamento de Física,
Universidade Federal de Pernambuco 50670-901, Recife PE, Brazil.
19 - Simulation and analytical results of vortex-antivortex motion in a corbino disk with a
magnetic dipole on top.
Belisa Rebeca Cavalcanti Holanda Tavares de Aquino, Leonardo R.E. Cabral, Clécio C. de Souza
Silva, J. Albino Aguiar, Milorad V. Milosevic, Francois M. Peeters.
Departamento de Física, Universidade Federal de Pernambuco, Av. Prof. Moraes Rego 1235,
Cidade Universitária, Recife PE, CEP 50670-901, Brazil.
8

Departement Fysica, Universiteit Antwerpen, Groenenborgerlaan 171, B-2020 Antwerpen,
Belgium.
20 - Síntese e caracterização estructural de partículas de ferro.
Ricardo Batista do Carmo, B.A.G. Rodríguez, J. Albino Aguiar.
Universidade Federal de Pernambuco, Av. Prof. Moraes Rego 1235, Cidade Universitária, CEP:
50670-901, Recife PE, Brazil.
21 - Characterization and study of superconducting properties of multilayer thin films.
Flávia Santos Portela, L.T. Corredor, Petrucio Barrozo, J. Albino Aguiar.
Universidade Federal de Pernambuco, Departamento de Física, 50670-901, Recife PE, Brazil.
22 - Polarized Raman spectroscopy in LaFeAsO system.
Ulisses Ferreira Kaneko, P.F. Gomes, A.F. Garca-Flores, D. Vaknin, E. Granado.
Universidade Estadual de Campinas, 21 Carlos Gerin st., Campinas SP, Brazil.
Ames Laboratory, US-DOE, Ames, Iowa 50011, USA.
23 - Superconductivity and magnetism in the K x MoO 2-δ .
Leandro Marco Salgado Alves, C.A.M dos Santos, S.S. Banaion, C.M. Romanelli, A.J.S. Machado,
B.S. de Lima.
Escola de Engenharia de Lorena, Universidade de São Paulo, Pólo Urbo-Industrial Gleba AI-6,
Fazenda Mondezir, Lorena SP, Cep 12600-970, Caiza Postal 116, Brazil.
24 - Hematite sub-micron hollow spheres: Thermal formation and magnetic properties.
L. De Los Santos Valladares, L. León Félix, A. Bustamante Domínguez, M. Espinoza Suárez, J.
Albino Aguiar. T. Mitrelias, C.H.W. Barnes.
Cavendish Laboratory, University of Cambridge, J.J. Thonson Av., Cambridge CB3 0HE, UK.
Laboratório de Superconductividade e Materiais Avançados, Departamento de Física,
Universidade Federal de Pernambuco 50670-901, Recife PE, Brazil.
Núcleo de Física Aplicada, Instituto de Física, Universidade de Brasilia, Brasilia DF 70910-900,
Brazil..
Laboratorio de Cerámicos y Nanomateriales, Facultad de Ciencias Físicas, Universidad Nacional
Mayor de San Marcos, Ap. Postal 14-0149, Lima, Peru.
25 - Synthesis and characterization of nanoparticles of cobalt ferrite for inmobilization.
Priscyla Lima de Andrade, V.A.J. Silva, J.C. Maciel, N.O. Moreno, S.M.B. Pereira, M.P.C. Silva, J.
Albino Aguiar.
Universidade Federal de Pernambuco, Rua Itaimbé, 23 IPSEP, Recife PE, Brazil.
Departamento de Física, Universidade Federal de Sergipe, São Cristovão, Brazil.
Departamento de Biologia, Universidade Federal Rural de Pernambuco, Recife, Brazil
9

26 - Preparation and characterization of fucan-coated magnetite nanoparticles for
application on antitumor activity.
Valdeene Albuquerque Jansen da Silva, P.L. Andrade, A.G. Bustamante Domínguez, M.M.
Quien, I.A. Souza, K.P.S. Cavalcanti, M.P.C. Silva, J. Albino Aguiar.
Universidade Federal de Pernambuco, Av. Pror. Moraes Rego 1235, Cidade Universitária,
Recife PE, CEP 50670-901, Brazil.
Laboratorio de Imunopatologia Keizo Asami (LIKA), Departamento de Bioquímica, Universidade
Federal de Pernambuco, Recife PE, Brazil.
Laboraotrio de Cerámicos y Nanomateriales, Universidad Nacional Mayor de San Marcos, Lima,
Peru.
Hospital das Clinica, UFPE, Brazil.
27 - Localized superconductivity near magnetic disks embedded in thin films.
Tiago T. Saraiva, Clécio C. de Souza Silva.
Departamento de Física, Universidade Federal de Pernambuco, Recife PE, Brazil.
28 - The Electrical, magnetic and structural properties of the system La 2 CoMnO 6 prepared by
the method of combustion after different atmosphere and treatment setup.
Pedro Linhares Filho.
Universidade Federal de Pernambuco, Av. Prof. Moraes Rego 1235, Cidade Universitária, CEP:
50670-901, Recife PE, Brazil.
29 - Application of a phenomenological model for the surface impedance in high
temperature superconducting films.
Ariday Samit Mosquera Polo, D.A. Landínez Téllez, L.T. Corredor, J. Albino Aguiar.
Universidade Federal de Pernambuco, Av. Prof. Moraes Rego, 1235, Cidade Universitária,
Recife PE, CEP 50671-901, Brazil.
30 - Study of the magnetic properties, the crystal, electronic and band structures of the
Sr 2 DyRuO 6 Complex Perovskite
C. A. Triana*, D. A. Landínez Téllez and J. Roa-Rojas
Grupo de Física de Nuevos Materiales (GFNM), Departamento de Física, Universidad Nacional
de Colombia,Bogotá D.C. Carrera 45 No 26-85, A.A. 5997, Colombia.
31 - Magnetotransport and magnetization measurements in melt-textured YBaCuO
superconductors probed by pulsed magnetic fields
Fábio Teixeira Dias, Valdemar das Neves Vieira, Douglas Langie da Silva, Sabrina Esperança
Nunes, Frederik Wolff-Fabris, Erik Kampert, Jacob Schaf, Joan Josep Roa Rovira
Universidade Federal de Pelotas, 96010-900, Pelotas, BrazilL.
Dresden High Magnetic Field Laboratory, HZ Dresden-Rossendorf, 01314, Dresden, Germany.
Universidade Federal do Rio Grande do Sul, 91501-970, Porto Alegre, Brazil.
Université de Poitiers, 86962, Poitiers, France.
10

32 - Possibility of the superconducting behavior in a new compound of Mg 2 SnB x C x
composition.
H. L. Santana, S. Renosto and A. J. S. Machado.
Escola de Engenharia de Lorena – EEL – USP.
33 - Synthesis and characterization of KMo 4 O 6 .
Margareth Andrade.
Escola de Engenharia de Lorena, Universidade de São Paulo, Polo-Urbo Industrial Gleba AI-6,
s/n, Brazil.
11

MINICOURSES
12

MINICOURSES
Magnetic characterization of superconducting materials
Fábio T. Dias
Universidade Federal de Pelotas
Since their discovery, several techniques have been applied to characterize
superconducting materials. Superconducting materials may be grown by several
techniques, resulting in polycrystalline samples, obtained by sintering and melttexturing
techniques, and thin films, obtained, for example, by chemical solution
deposition, among others. Melt-textured materials and thin films are among of the most
prominent materials to technological applications.
The magnetic characterization arises as a very important tool in order to obtain
relevant information about interesting properties, such as flux pinning capability,
critical current density, critical temperature, critical fields, vortex dynamics, magnetic
irreversibilities, time effects, etc.
This minicourse is focused in basic aspects of the magnetic characterization of
high temperature superconductors, with emphasis in thin films and melt-textured
materials. Experimental results are discussed in terms of the basic phenomenology and
magnetic properties.
13

Solução numérica das equações de Ginzburg-Landau pelo método de
variáveis de ligação
Edson Sardella
1
UNESP - Universidade Estadual Paulista, Departamento de Física, Faculdade de Ciências,
Caixa Postal 473, 17033-360, Bauru-SP, Brazil
Neste mini-curso apresentamos um método numérico de solução das equações de
Ginzburg-Landau. Com esta finalidade, usamos o método de variáveis de ligação. Este
método consiste em reescrever as equações de Ginzburg-Landau em termos de campos
auxiliares os quais garantem a invariância de calibre das equações, mesmo quando
discretizadas. Apresentamos também alguns exemplos de aplicação do método.
14

15
MINICOURSES
Mössbauer spectroscopy for materials science: The aging effect in
superconductor CaLaBa{Cu 1−x Fe x } 3 O 7−δ with 0≤ x ≤0.07.
Angel Bustamante 1
1 Laboratorio de cerámicos y nanomateriales, Universidad Nacional Mayor de San Marcos,
Lima, Peru.
The Mössbauer effect is the emission and absorption resonant recoilless nuclear gamma
rays and corresponds to the zero-phonon transition. The term recoilless is interpreted as
the crystal as a whole suffers a recoil almost negligible. Mössbauer effect is likely to
happen and corresponds to the factor f which depends on the temperature. To this effect
and using the Doppler velocity hyperfine interactions detected as the isomer shift (IS)
which is due to the finite size of the nucleus and the term expansion monopolar
electrostatic interaction energy between nucleus, total electric charge Ze distributed
over the nuclear volume density N (r) at point r and an electrical potential V(r) due to
the loads on the environment. This interaction also displaces energy levels without
altering the transition energies of both the radioactive source which emits the gamma
ray absorber and provided in the oxidation state and coordination atom studied. The
second term in the expansion is the electric dipole between the electric dipole moment
and the electric field in the center of the core. This term is zero because the core does
not have electric dipole moment. The third term corresponds to the interaction of the
nuclear quadrupole moment with the electric field gradient (EFG) produced by an
asymmetric distribution around the nucleus charges (electrons, ions, dipoles, etc.) and is
the cause of the degeneration partially unfold 2I + 1 nuclear levels and for the case of
Fe 57 with fundamental level, I g =1/2, that unfolds, and excited, with I e =3/2, is split into
two sublevels with m 3/2 = 3/2 and 1/2, two lines shown in the Mössbauer spectrum
whose separation is called quadrupole splitting QS or E Q , and provides information on
the oxidation state and coordination number of the distortion of the crystal lattice.
Nuclei with nuclear magnetic moment can interact with a magnetic field H which can
be a field external or internal fields o hyperfine fields H hf that can be produced by the
spin and the unpaired electrons (dipole field), the angular moment produced by the
orbital electrons. Electrons "s" and those who are not full layers contribute to this
component (orbital field) and produced by electrons "s" that penetrate the nucleus
(Fermi contact field). The magnetic interaction completely breaks the degeneracy of the
nuclear spin levels I0 and unfolded each level 2I+1 equally spaced sublevels. The
allowed transitions between these sublevels are governed by the selection rules
m I =0,1 andI =1. The experimental arrangement for the case of iron considered a
radioactive Co 57 source in a matrix of Rhodium which emits 14.4 Kev gamma ray, an
absorber containing iron, a multichannel analyzer 512 or1024 channels and a software
for fitting spectra. In this talk, we will present an introduction to Mössbauer
spectroscopy an the long-term aging effect caused by Fe atoms in the superconductor
CaLaBa{Cu 1−x Fe x } 3 O 7−δ with 0 ≤ x ≤ 0.07. XRD confirms that this system has a
YBCO-like structure. The critical temperature (Tc) is strongly affected by aging and
depends on the amount of Fe in the structure. Room temperature Mössbauer
spectroscopy reveals the presence of the typical species A, B–B´, C and new species
E´and F. Interestingly; A, which corresponds to the Fe 3+ atom located in the Cu(1) of
the chains with spin S z = 3/2, shows a drastic reduction which means migration to the
species B, B´ and C. Species B and B´correspond to the Fe 3+ in the Cu(2) site forming
planar quasi-octahedral and planar square pyramidal, while the C specie is a square
pyramidal with O(5) respectively (spin S z = 3/2 in all these cases). Aging causes loss of
superconductivity in the samples with 5 and 7% of iron content.

Some remarks on synthesis, structural characterization and
measurements of the physical properties of superconducting pnictides
Sergey L. Bud’ko
Ames Laboratory US DOE, and Department of Physics and Astronomy, Iowa State
University, Ames, Iowa 50011, USA
I will present a brief general overview on synthesis and structural/compositional
characterization of superconducting pnictides, mainly of the 122 family.
A need of experimental determination of the samples’ composition, miscibility
gap in Mn-doped BaFe 2 As 2 and other systems, effects of stresses on superconductivity,
bulk vs. filamentary superconductivity, coexistence of superconductivity and
magnetism, will be discussed and examples will be given.
16

MINICOURSES
Introduction to muon spin rotation and relaxation
Rustem Khasanov
Paul Scherrer Institut, Switzerland
Over the past decades muon spin rotation techniques (muSR) have established
themselves as an invaluable tool to study a variety of static and dynamic phenomena in
bulk solid state physics and chemistry. Common to all these approaches is that the muon
is utilized as a spin microprobe and/or hydrogen-like probe, implanted in the material
under investigation. Recent developments extend the range of application to deeply in
the bulk allowing to perform experiments under the high pressure as well as near the
surface allowing to perform nanometer scale depth resolved experiments on the thin
films and super-lattices. After briefly summarizing the production of so called surface
muons used for bulk studies, and discussing the principle differences between pulsed
and continuous muon beams, the production of keV-energy muon sources will be
discussed. A few topical examples from different active research fields will be
presented to demonstrate the power of these techniques.
17

Measuring the thermal expansion of solids: How is it done, and how
can it be used to study phase transitions?
John J. Neumeier
Department of Physics, Montana State University, Bozeman, Montana, USA
We have developed an instrument for measuring the thermal expansion of solid
materials, with a resolution of about 0.1 angstroms. It has been used to measure very
complex materials such as quasi‐one‐dimensional compounds, important magnetic
materials, superconductors and some elements. The results reveal a number of surprises
as well as important information connecting structural and physical properties. In this
presentation, I’ll describe the instrument in detail, highlight some results, and describe
how thermal expansion can be used as a tool to study phase transitions.
18

MINICOURSES
Introduction to thermoelectric properties of solids
Joshua L. Cohn
University of Miami, Physics Department, Coral Gables, FL 33124, USA
A survey of the Seebeck coefficient of solids will be presented, with a particular focus
on the magnitudes and temperature dependencies expected from simple theoretical
considerations and what insights can be gained from its measurement in metals and
superconductors. The separate contributions from charge-carrier diffusion and phonon
drag will be emphasized.
19

Flux pinning in HT c superconductors
Adrian Crisan
School of Metallurgy and Materials, University of Birmingham, B15 2TT U.K.
The lecture start with a short introduction of the difference between type I and type II
superconductors, the characteristic lengths (penetration depth and coherence length), the vortex
(mixed) state, flux quanta (vortex), the Lorentz and pinning forces.
Several types of natural and artificial pinning centres will be then presented, especially
for thin films and coated conductors, with TEM images from nanostructured thin films
illustrating various types of defects (pinning centres).
The lecture will continue with the estimation of bulk pinning force (from critical current
density) from DC magnetization loops. Dew-Hughes model linking the type and dimensionality
of pinning centres with the field dependence of normalized pinning force will be explained,
with few examples (much more examples will be given in the shorter talk during Workshop).
Next it will be described the use of frequency-dependent AC susceptibility measurements to
estimate and model the average pinning potential, with few examples from my lab.
The lecture will draw a few important conclusions about the importance of pinning centres, their
nano-engineering, their properties, in correlation with structural analysis.
20

MINICOURSES
Técnicas de síntese de materiais supercondutores cerâmicos e
intermetálicos.
Prof. Dr. Antonio Jefferson da Silva Machado
EEL - USP
A qualidade de um material supercondutor está diretamente relacionada com a
técnica escolhida para a sua síntese. Neste mini-curso iremos discutir as técnicas que
são normalmente empregadas para a produção de materiais policristalinos e
monocristais de alta qualidade. O emprego de diagrama de fases termodinâmico,
técnicas de crescimento de monocristais pelo método do fluxo, o método Czochraslki de
crescimento, produção de materiais policristalinos pela tecnologia do pó e algumas
técnicas de crescimento de filmes finos serão discutidos.
21

From your laboratory to publishable neutron data. Obtaining high
quality results
Juscelino B. Leão
NIST Center for Neutron Research, National Institute of Standards and Technology,
Gaithersburg, MD 20899, USA
A first order summary of gathering and analyzing powder neutron diffraction data will
be presented considering that these techniques may also be applicable for x-ray data.
There are many factors that affect the success of data gathering at a large neutron or x-
ray facility. Considering such factors prior, during and after the data collection will
significantly increase the results of a visit to a facility such as the NIST Center for
Neutron Research
22

ORAL CONTRIBUTIONS
ABSTRACTS
ORAL CONTRIBUTIONS
23

Time reversal symmetry breaking and the unusual magnetic order in
pseudogap state
Alfredo A. Vargas-Paredes 1 , Marco Cariglia 2 and Mauro M. Doria1*
1 Instituto de Física, Universidade Federal do Rio de Janeiro RJ Brazil
2 Departamento de Física , Universidade Federal de Ouro Preto MG, Brazil
* mmd@if.ufrj.br
The origin of the pseudogap in the high temperature cuprate superconductors is being
unveiled through ARPES (angle resolved photoelectron spectroscopy) experiments by
the use of circularly polarized photons. Left-circularly polarized photons give a different
photocurrent from right-circularly polarized photons (dichroism), indicating that timereversal
symmetry is spontaneously broken at the pseudogap temperature onset (T*),
which indeed corresponds to a phase transition. Polarized neutron diffraction
experiments have shown that this characteristic temperature T* also marks the onset of
an unusual magnetic order. Nernst effect and other experiments indicate that preformed
Cooper pairs exist above the critical superconducting temperature (Tc

ORAL CONTRIBUTIONS
Magnetic field profile of a mesoscopic superconducting SQUID: a
study by using Ginzburg-Landau theory
F Rogeri 1 , R Zadorosny 2 , P N Lisboa-Filho 1 , E Sardella 1;3 , W
A Ortiz 4
1
UNESP-Universidade Estadual Paulista, Departamento de F__sica, Faculdade de Ciências,
Caixa Postal 473, 17033-360, Bauru-SP, Brazil, E-mail: sardella@fc.unesp.br
2
Departamento de F__sica e Qu__mica, Faculdade de Engenharia de Ilha Solteira, UNESP-
Universidade Estadual Paulista, Caixa Postal 31, 15385-000 Ilha Solteira-SP, Brazil.
3
UNESP-Universidade Estadual Paulista, IPMet-Instituto de Pesquisas Metrológicas, CEP
17048-699 Bauru-SP, Brazil.
4
Departamento de Física, Universidade Federal de S~ao Carlos, 13565-905, São
Carlos-SP, Brazil
In this paper we study the local magnetic field profile of a mesoscopic superconductor
with a geometry designed like a SQUID, a square with a hole at the center connected to
the outside vacuum through a very thin slit. We have carried out our investigation both
in the Meissner and the mixed state. We also studied the influence of the temperature on
the magnetic field distributions.
25

Limitation of ac electrical current by SmBa 2 Cu 3 O 7-d ceramic
C. A. C. Passos 1 , M. T. D. Orlando 1 , V. A. Rodrigues 1 , V. T. Abilio 1 , G. M. Silva 1 , L. C.
Machado 1 .
1 Universidade Federal do Espirito Santo, Vitoria - ES, 29075-910, Brazil
The development of devices to protect electrical systems has increased due to the need
of improving stability and reliability of these systems. Specific attention is given to the
designs and application of high-Tc superconductor. Advances in the synthesis
procedures of polycrystalline HTSC materials has stimulated the development of
Superconducting Fault Current Limiter (SFCL) device. Most fault current limiter
prototypes are based on YBa 2 Cu 3 O 7 - d ceramic with critical temperature Tc = 92 K or
with Bi 2 Sr 2 Ca 2 Cu 3 O 8+d cuprates where Tc = 110 K. However, another promising
compound is SmBa2Cu3O7-d (Sm-123) superconducting ceramic. Our initial studies of
a resistive SFCL based on Sm-123 have confirmed the capability of limiting the fault
current. At a fault event, the fault current value was reduced from 8.2 A peak to 6.6 A peak .
The prospective/limited of current ratio observed in this experiment was ~1.2 for a 2.4
mm thick sample. These results will be applied to determine optimal condition in the
superconducting fault current limiter (SCFL) devices based on Sm-123 ceramics.
26

ORAL CONTRIBUTIONS
MagLev-Cobra: A Brazilian Magnetically Levitated Vehicle
Guilherme Gonçalves Sotelo 1 , Daniel Henrique Nogueira Dias 1 , Rubens de Andrade Jr. 2 ,
Richard Magdalena Stephan 2
1 Universidade Federal Fluminense
2 Universidade Federal do Rio de Janeiro
A magnetically levitated (MagLev) transport system is under development at the
Laboratory for Applied Superconductivity (LASUP) in Rio de Janeiro. This vehicle is
entitled MagLev-Cobra (“cobra” means snake in Portuguese), because it is composed by
several modules and during the curves it resembles the movement of a snake. The main
application of this vehicle is the people urban transportation, one important problem in
big cities. The technology adopted for this vehicle consists of levitating high
temperature bulk superconductors (HTS) above an external magnetic field, whose origin
is a guideway made with Nd-Fe-B and steel. This technology has been extensively
studied for more than 12 years by researchers of LASUP. The bulk superconductors are
located inside cryostats and they are cooled by liquid nitrogen (LN2). This
superconducting levitation was adopted due to the following reasons:
• it is possible to levitate a mass of approximately 1000kg at a 10mm gap spending
energy only for refrigerating the HTS bulks (four cryostats with 20 liters of LN2 keep
this mass levitating during approximately one day);
• the high cost of the magnetic guideway is compensated by the high frequency of the
vehicles circulating along the line;
• the civil engineering costs are much lower than that necessary for subways.
A linear induction motor was designed and constructed for the vehicle’s traction.
This special motor was projected to produce force in the vertical direction, helping the
levitation, besides the traction force. The main advantages of MagLev-Cobra vehicle
are: low energy consumption, negligible noise emission, curvature radius of 50 meters
and capability to ascend ramps of 15%. These properties allow the vehicle to be
perfectly adjusted to cities layout and to be constructed along roads and rivers profiles.
The first unit of a functional prototype was finished recently. In this work, some initial
tests of this unit are presented.
27

Multicanonical distribution: applications to flux avalanches in
superconductors
Giovani L. Vasconcelos (a) and Domingos S. P. Salazar (b)
(a) Departamento de Física, Universidade Federal de Pernambuco, Recife, Brazil
(b) Unidade de Educação a Distância e Tecnologia, Universidade Federal Rural de
Pernambuco, Recife, PE, Brazil
A general theoretical framework―the multicanonical distribution―is presented in
which probability distributions with power-law tails naturally arise as a consequence of
the existence of a hierarchy of time and length scales in the underlying dynamics of the
system. Our formalism is based on a few basic assumptions: (i) at large scales the
distribution is of exponential form which includes Gaussian and Poissonian processes as
particular cases; (ii) at short scales the distribution can be represented as a mixture of
the large-scale distribution where the relevant parameter―which can be viewed as a
scale-dependent temperature―is a fluctuating quantity; (iii) the fluctuating dynamics of
the short-scale "temperature" is described in terms of a set of nested "internal heat
reservoirs'', where the energy exchange between adjacent reservoirs is modelled by an
appropriate stochastic process. From these assumptions it is possible to derive an
analytic expression for the resulting probability distribution function in terms of
generalized hypergeometric functions of the type n F 0 , which form the most general
family of probability distributions with finite variance and power law tails. Applications
of our model to turbulence and other complex systems will be briefly discussed. In
particular, it will be argued that our multicanonical formalism may provide a theoretical
basis for understanding the power law distribution of flux avalanche sizes recently
observed (Qviller et al., Phys. Rev. X 2012) in superconducting films.
.
28

ORAL CONTRIBUTIONS
Madelung Energy of Regular Lattices
P. C. N. Pereira and S. W. S. Apolinario
Departamento de Fisica, Universidade Federal de Pernambuco, 50670-901 Recife, PE, Brazil
Due to strong Coulomb repulsion, an electron gas at low temperature and
density undergoes a phase transition to a crystalline state called the Wigner crystal, as
predicted theoretically by Eugene Wigner in 1934. The Wigner crystal is one of the
possible ground states of a strongly correlated electron system. Wigner crystallization
was first observed in an electron gas confined above the surface of liquid helium by
Grimes and Adams. Several theoretical and experimental works have considered the
properties of a finite number of particles interacting through a repulsive interparticle
interaction potential and kept together by an external confinement potential. Typical
experimental realizations of such 2D systems include electrons on the surface of liquid
helium, vortices in a type II superconducting 2D films, colloidal suspensions, and dusty
plasma crystals. These systems and their configurations have been observed
experimentally, and depending of their conditions, they can form regular lattices.
We propose a method to compute the Madelung energy (ME) of regular lattices.
As a first test, such a method was applied for Yukawa lattices [1] of different topologies
and dimensions which resulted in an approximate closed form expression of the ME.
The obtained Madelung energies have a satisfactory accuracy for all ranges of the
screening parameter κ of the Yukawa potential, and it becomes exact in the asymptotic
limits κ→0 and κ→+∞. For instance, for the triangular lattice, the maximum relative
error of the ME given by the method is about 0.0047. Also, satisfactory results are
obtained for the one-component plasma limit. The Madelung constants of the twodimensional
hexagonal BN and square NaCl and the three-dimensional cubic NaCl
crystals are estimated with a relative error of 0.004, 0.006, and 0.03, respectively.
Finally, different ways to improve the method are presented and discussed.
[1] Medelung energy of Yukawa lattices, P. C. N. Pereira and S. W. S. Apolinario,
Phys. Rev. E 86, 046702 (2012).
29

Spin current phenomena: new impetus to Spintronics
Sergio Machado Rezende
Departamento de Física, Universidade Federal de Pernambuco, Recife, PE, Brazil
In recent years several phenomena have been discovered in magnetic nanostructures in
which the transport of carriers depends on their spin. In addition to the long time known
charge and heat currents, these phenomena also involve spin currents. Among them
there are the spin Hall effect (SHE), the inverse spin Hall effect (ISHE) and the spin
Seebeck effect (SSE). These effects make possible the conversion from one type of
current to another in very efficient processes opening new possibilities for the
development of spintronics. We will review recent developments in this area and
present new results obtained with the spin Hall and spin Seebeck effects.
.
30

ORAL CONTRIBUTIONS
Vortex-antivortex configurations in thin superconducting disks with an
out-plane magnetic dipole
Leonardo R. E. Cabral
Departamento de Física, Universidade Federal de Pernambuco, Av. Prof. Moraes Rego, 1235 -
Cidade Universitária, Recife-PE, 50670-901, Brazil
Vortex configurations in thin films [1] and mesoscopic disks [2,3] in the presence of
ferromagnetic dots have been studied and it is shown that vortex-antivortex patterns
may be observed. In films the vorticity of vortices and antivortices should be the same,
whereas different vorticity values for vortices and antivortices are allowed in disks,
provided they are small enough. In this talk we revisit this system within the framework
of the London approach for the case of negligible demagnetization effects. We study the
stable vortex configurations in superconducting disks in the presence of an
inhomogeneous magnetic field produced by an out-plane magnetic dipole placed at the
disk main axis. The shielding currents generate a confinement potential for stable
vortices configurations. In some circunstances, configurations containing both vortices
and antivortices can be obtained. These configurations are calculated numerically by
solving the Bardeen-Stephen equation of motion for vortices. In the case of highly
symmetrical configurations - i.e., those where the ratio of the number of vortices and
antivortices in different shells is an integer and there are more than one antivortex - we
obtain a set of algebraic equations for the vortex and antivortex positions which can be
solved numerically. When the number of vortices and antivortices in different shells are
the same anallytical expressions yield good approximations for the vortex and
antivortex positions, provided they are far from the disk edge.
[1] M. V. Milošević, S. V. Yampolskii, and F. M. Peeters, Phys. Rev. B 66, 174519
(2002).
[2] M. V. Milošević, S. V. Yampolskii, and F. M. Peeters, Phys. Rev. B 66, 024515
(2002).
[3] M. V. Milošević and F. M. Peeters, Phys. Rev. B 68, 094510 (2003).
31

Stabilizing composite vortex states in hollow cylinders
Antonio R. de C. Romaguera
Departamento de Física, Universidade Federal Rural de Pernambuco, Av. Dom Manoel de
Medeiros s/n, Dois Irmãos, CEP: 52171-900 Recife, PE, Brasil
In this work we studied the composite vortex states using the Two-Band Ginzburg-
Landau theory. We solve the first GL equation for large κ in a cylinder of inner radius
Ri, outer radius Ro and thickness t, immersed in a homogeneous applied field. A well
known behavior in superconductors is that we cannot pin a vortex line in a hole with
radius below a certain value. For our system, depending of the values of the radii, the
cylinder can pin a different number of vortices in each band. This behavior is an
experimental path to stabilized and measure composite vortex states. For this work we
also numerically obtained the phase diagram Ri versus the ratio of coherence lengths in
each band in order to propose a candidate experimental system with its physical
dimensions.
32

ORAL CONTRIBUTIONS
Penetration of magnetic field in type II superconductors studied by
time dependent Ginzburg-Landau equation
Isaias G. de Oliveira
Departamento de Física, Universidade Federal Rural de Rio de Janeiro BR-465, km 7, CEP
2389-000, Seropedica, Rio de Janeiro, Brazil
The time-dependent Ginzburg-Landau (GL) equation is solved numerically for type-II
superconductors using the finite element method [1][2]. The size of the mesoscopic
sample, the GL parameter, and the applied magnetic field have a marked influence on
the petration of the magnetic field, the magnetic vortex distribution and the vortex
dynamics. In this workshop I will present different behaviors of magnetic field
penetration in superconductors:
1. For large sample (Lx = 100λ and Ly = 50λ) with ĸ = 4, and subjected to an
uniform magnetic field H = 1.5H c2 . The initial penetration of magnetic field
presents usual penetration behavior. After few times the penetration of magnetic
field presents a new behavior, when so, appear small structures: the magnetic
fingers. They increace until there exist nucleation of vortices on the top of these
fingers. The magnetic fingers structure are destroyed however it returns to
increace again. The vortices nucleated are driven to the centre of the sample
pushed by the giant vortices fingers.
2. For a mesoscopic superconductor square with slit and hole [3]. In this case I
have studied the vortices penatration for different values of _ and applied
magnetic field. For soft type II superconductors (for instance, ĸ = 3) there are a
penatration of multivortices and the system find the stability so fast. Otherwise,
for extremely hard superconductors (for instance, ĸ = 20), there are nucleations
of multivortices and also appear giants vortices in the corners of the hole. From
these giants vortices in the corners multivortices are nucleated.
3. Presence of defects. To illustrate the dynamics of vortices entering a defect in a
square shaped type-II superconductor, I will present the time evolution of
vortices for different values of ĸ and applied magnetic field. The applied field is
kept constant, after the system arrive in a stable configuration the magnetic field
is inverted. By this time we can see three simultaneous effects: penetration of
anti-vortices, expelling of vortices and annihilation of vortex and anti-vortex.
[1] The software Comsol 3.5a and MatLab have been used for numerical calculations.
[2] T.S. Alstrøm et al., Acta Appl Math DOI 10.1007 , August 2010.
[3] E. H. Brandt, Journal of Low Temperature Physics, Vol. 130, Nos. 3/4,
February 2003
33

Study of the phase formation on YBa 2 Cu 3 O 7-x coatings after sintering
at different temperatures
A. Bustamante D. 1 , H. Sánchez C. 1 , J. Garcia D 1 . A. Osorio A. 2 , M. Mejía S. 1 , L. León F. 1,3 , L.
De Los Santos Valladares 4,5 and J. Albino Aguiar 5
1
Facultad de Ciencias Físicas, Universidad Nacional Mayor de San Marcos, Ap. Postal 14-0149,
Lima 14, Perú.
2
Facultad de Química e Ingeniería Química, Universidad Nacional Mayor de San Marcos, Perú.
3 Núcleo de Física Aplicada, Instituto de Física, Universidade de Brasília, Brasília, DF 70910-900,
Brazil.
4 Cavendish Laboratory, Department of Physics, University of Cambridge, J.J. Thomson Av.,
Cambridge CB3 0HE, United Kingdom.
5 Laboratório de Supercondutividade e Materiais Avançados, Departamento de Física
Universidade Federal de Pernambuco 50670-901, Recife PE, Brazil.
In this work we report the growth of YBa 2 Cu 3 O 7-d (YBCO) deposited on SrTiO 3
substrate by the chemical deposition method. The precursor was obtained by sol-gel,
deposited onto the substrate and subjected to calcinations and sintering processes at the
same time. During the sintering heat treatment, the oxygen atmosphere was carefully
controlled in order to maintain the oxygen stoichiometry invariant. The sintering was
performed for 36 h, 12 h of which the temperature was maintained stable. The
calcinations and sintering were performed at three different temperatures: 820 ºC, 840
ºC and 860 ºC. The characterization was made by X-ray diffraction (XRD), which
confirmed the formation of YBCO. The magnetic signals using a MPMS-SQUID
showed that the critical superconducting temperature were 90K all the samples,
confirming the formation of the YBCO superconductor. We also present the reoxygenation
process on the YBCO film by sintering at 600 °C under oxygen flow for 4
hours. The characterization is made through XRD, using a θ-2θ geometry to study the
growth stage of the film, while θ sweeps are performed to study the degree of the
roughness and texture of the film. The results obtained are compared with a previous
work [2]. It shows a clear effects, especially in the growth of the secondary phases of
the film such as the Y 2 BaCuO 5 (Y211, green phase) where the reflections (321) and
(403) are more noticeable. Furthermore other intense peaks are observed such as (00l),
(005) and (006). A "Rocking Curve" analysis (sweeping θ) around the (005) reflection
was performed, where a half width of 0.43° was observed confirming a good orientation
on the c-axis.
34

ORAL CONTRIBUTIONS
Electric field-assisted consolidation of (Bi,Pb) 2 Sr 2 Ca 2 Cu 3 O 10+y ceramic
samples
E. Govea-Alcaide 1 , I. F. Machado 2 , P. Muné 3 , and R. F. Jardim 4
1
Departamento de Ciencias Básicas, Facultad de Ciencias, Técnicas, Universidad de Granma,
Apdo. 21, P. O. Box. 85100, Bayamo, Cuba, e-mail: egoveaa@udg.co.cu
2 Departamento de Engenharia Mecatrônica e Sistemas Mecânicos, Escola Politêcnica,
Universidade de São
Paulo, 05508-900, São Paulo, SP, Brazil, e-mail: machadoi@usp.br
3 Departamento de Física, Universidad de Oriente, Patricio Lumumba s/n, P.O. Box 90500,
Santiago de Cuba, Cuba, e-mail: mune@cnt.uo.edu.cu
4 Instituto de Física,Universidade de São Paulo, CP 66318, 05315-970, São Paulo, Brazil, e-
mail: rjardim@if.usp.br
Pre-reacted powders of Bi 1.65 Pb 0.35 Sr 2 Ca 2 Cu 3 O 10+y (Bi-2223) were consolidated by
using the spark plasma sintering (SPS) technique. The influence of the consolidation
temperature, TD, on the structural and electrical properties has been investigated and
compared with those of a reference sample synthesized by the traditional solid-state
reaction method and subjected to the same compacting pressure. The uniaxial
compacting pressure used in all samples was 50 MPa. From the X-ray diffraction
patterns, performed in both powder and pellet samples, we have found that the dominant
phase is the Bi-2223 in all samples, but traces of the Bi 2 Sr 2 CaCu 2 O 8+y (Bi-2212) were
identified. Their relative density were ~ 85 % of the theoretical density. The
temperature dependence of the electrical resistivity, ρ(T), indicated that increasing TD
results in samples with low oxygen content because the SPS is performed in vacuum.
Features of the the ρ(T) data, as the occurrence of normal-state semiconductor-like
behavior of ρ(T) and the double resistive superconducting transition, are consistent with
samples comprised of grains with shell-core morphology in which the shell is oxygen
deficient. In addition, the SPS samples also exhibited superconducting critical current
density at 77 K, Jc(77K), between 2 - 10 A/cm2, values much smaller than ~ 22 A/cm2
measured in the reference sample. Re-oxygenation of the SPS samples, post-annealed in
air at different temperatures and times, was found to improve their microstructural and
transport properties. Besides the suppression of the Bragg peaks belonging to the Bi-
2212 phase, the superconducting properties of the post-annealed samples and
particularly Jc(77K) were comparable or better than those corresponding to the
reference sample. Post-annealed samples at 750 oC for 5 min exhibited Jc(77K) ~ 130
A/cm2 even when uniaxially pressed at only 50 MPa.
35

Synthesis and superconducting properties on the Ta-Zr-B system.
Custodio Ramalho M 1 , Z. Fisk 2 and A. J. S. Machado 1
1 Escola de Engenharia de Lorena, Universidade de São Paulo, P.O. Box 116, Lorena, SP,
Brazil.
2 Departments of Physics and Astronomy, University of California at Irvine, Irvine, CA 92697,
USA.
Since the discovery of the superconductivity in MgB 2 a renew interest in borides
systems have increased in the last years. The interesting in the boride systems is how
rare is the superconductivity occurrence. Many MRB 2 (MR – Refractory metal)
crystallize in the same prototype structure than MgB 2 type AlB 2 . However just NbB 2 is
a known superconductor material with superconducting critical temperature close to 3.9
K. However there are many prototype structures in which some boride of refractory
metals can crystallize. Within this scenario the prototype structure of U 3 Si 2 is a
interesting structure which can be favorable for superconductivity. So in this work we
will show results which suggest the existence of a new class of borides materials. This
new material class can crystallize on the U 3 Si 2 prototype structure and a systematic
study of the synthesis of Ta 3-x Zr x B 2 with an interval of 0 ≤ x ≤ 0.3. These results
strongly suggest that this compound is a superconducting material where the
superconducting critical temperature is dependent of the Zr content. Results of
magnetization as a function of temperature, resistivity as a function of temperature,
specific heat and x-ray analysis are shown. These results represent the observation of
superconductivity by the first time for this kind of prototype structure.
36

ORAL CONTRIBUTIONS
Possibility of unconventional behavior in a new superconductor
material of Zr 1-x V x B 2 compounds.
S.T. Renosto 1 , O.V. Cigarroa 1 , Z. Fisk 2 , C.A.M. Santos 1 , J.A. Aguiar 3 , S.G. Jung 4 , J.
Vanacken 4 , V.V. Moshchalkov 4 , A.J.S. Machado 1
1 Escola de Engenharia de Lorena, Universidade de São Paulo,P.O. Box 116, Lorena – SP,
Brazil.
2 Departament of Physics and Astronomy, University of Califórnia at Irvine,92697, Irvine – CA,
USA.
3 Departamento de Física, Universidade Federal de Pernambuco, Recife – PE, Brazil.
4 Institute for Nanoscale Physics and Chemistry, K. U. Leuven Celest. 200 D, B-3001 Leuven,
Belgium;
Since the discovery of superconductivity in MgB2 with superconducting critical
temperature close to 40 K, MB2 materials (M = Transition Metal) with the same
prototype structure AlB2 are considered as candidates for multiband superconductivity.
In this group, the ZrB2 compound exhibits Pauli paramagnetism at low temperature.
However, in this work we show results of a systematic study of the partial substitution
of Zr for V in the Zr1-xVxB2 (0.01 ≤ x ≤ 0.1) compositions which reveal that vanadium is
able to induce superconductivity in this compound with superconducting critical
temperature reaching the maximum value of 8.7 K for Zr0.96V0.04B2 composition.
Measurements of the dependence of resistivity, magnetization and specific heat with
temperature for polycrystalline samples, and magnetization versus temperature for
single crystal sample, confirm the superconducting transition close to 9.0 K. These
results reveal the strongly deviation from conventional (BCS) behavior through of
specific heat and transport measurements. We were found a possibility of an
unconventional behavior in the negative curvature of the Hc1 versus reduced temperature
(T/Tc) phase diagram, which suggest multiband behavior. This kind of behavior it is
relatively common in compounds which crystallize in AlB2 prototype structure. Indeed,
these suspect is verify in magnetization versus temperature for single crystal of this
material, where we can observe a second transition close to 3.0 K. Probably this is
consequence of the π band between boron-boron interaction, which is amplify with
vanadium doping which is smaller that zirconium atoms. Furthermore, the size of the
jump in the specific heat is smaller that the value predict by BCS theory.
37

Superconductivity of a new non-centrosymmetrical
material of YCoC 2 composition.
Cigarroa O.V. 1 ; Renosto S. 1 ; dos Santos C. A. M. 1 ; Fisk Z. 2 ;Machado A.J.S. 1 .
1 Escola de Engenharia de Lorena, Universidade de São Paulo, P.O. Box 116, Lorena, SP,
Brasil.
2 Departments of Physics and Astronomy, University of California at Irvine, Irvine, CA 92697,
USA.
Polycrystalline samples of YCoC 2 have been obtained with fusion on a tri-arc furnace
method. Structural, magnetic and electronic transport properties have been measured on
this material. Despite earlier studies claiming that this compound is a Pauli paramagnet,
superconducting properties have been discovered with a T C = 4.1 K. Measurements of
heat capacity versus temperature confirms that a bulk superconducting transition is
present.
38

ORAL CONTRIBUTIONS
Local mapping of dissipative vortex motion
B. Raes 1 , J. Van de Vondel 1 , A. V. Silhanek 2 , C. C. de Souza Silva 3 , J. Gutierrez 1 , R. B. G.
Kramer 4 , and V. V. Moshchalkov 1
1) INPAC–Institute for Nanoscale Physics and Chemistry, Nanoscale Superconductivity and
Magnetism Group,
KU Leuven, Celestijnenlaan 200D, B–3001 Leuven, Belgium
2) Département de Physique, Université de Liège, Allée du 6 aoˆut 17, B5, B–4000 Sart Tilman,
Belgium
3) Departamento de Fisica, Universidade Federal de Pernambuco, Cidade Universitaria,
50670-901 Recife-PE, Brazil
4) Institut Néel, CNRS, Université Joseph Fourier, BP 166, 38042 Grenoble Cedex 9, France
We explore, with unprecedented single vortex resolution, the dissipation and motion of
vortices in a superconducting ribbon under the influence of an external alternating
magnetic field. This is achieved by combining the phase sensitive character of ac
susceptibility, allowing us to distinguish between the inductive and dissipative
responses, with the local power of scanning Hall probe microscopy. Whereas the
induced reversible screening currents contribute only inductively, the vortices do leave a
fingerprint in the out-of-phase component. The observed large phase-lag demonstrates
the dissipation of vortices at time scales comparable to the period of the driving force
(i.e., 13 ms). These results indicate the presence of slow microscopic loss mechanisms
mediated by thermally activated hopping transport of vortices between metastable
states. This opens new and exciting possibilities to study locally loss mechanisms in a
variety of interesting magnetic systems (e.g., magnetic domain walls).
We acknowledge the Methusalem funding by the Flemish government and the Flemish
Science Foundation, FWO-Vl, for financial support. C.C.d.S.S. acknowledges support
from the Brazilian science agencies CNPq and FACEPE. J.V.d.V and J.G. acknowledge
support from FWO-Vl.
39

Effect of interface roughness on the superconducting transition
temperature of Nb/Co multi-layers
Y. T. Xing 1 , Liying Liu 2 , U. D. Chacón Hernandez 3 , , N. Midori Suguihiro 2 , W. Jaeger 4 , D.
Haeussler 4 , E. Baggio-Saitovitch 3 , I. G. Solórzano-Naranjo 2
1 Instituto de Física, Universidade Federal Fluminense, Niterói 24210-346, Brasil
2 DEMa, Pontifícia Universidade Católica do Rio de Janeiro, Rio de Janeiro, Brasil
3 Centro Brasileiro de Pesquisas Físicas, Rio de Janeiro 22290-180, Brasil
4 Institute for Materials Science, Christian-Albrechts-Universität zu Kiel, Germany
Superconductor (SC)/ferromagnet (FM) Nb/Co multi-layers have been produced with
magnetron-sputtering and the magnetic properties shows that with increase of the
thickness of Co layers (dCo) the superconducting transition temperature (Tc)
significantly increases. It was reported that when the thickness of the magnetic layers is
less than several nanometers, Tc increases and decreases periodically with the increase
of the thickness of the magnetic layers. In our samples, however, the thickness of the
magnetic layers (several tens nanometers) is much larger than that range and because of
the tray field and proximity effect, it was expected that the Tc of the samples will only
decreases with the increase of the Co layer thickness. In order to study the unusual
behavior, cross-section samples have been prepared to investigate microstructures of the
SC/FM interface by means of Atomic Force Microscopy (AFM), Electron Diffraction
and Transmission Electron Microscopy (TEM). The study shows that the interface
roughness (R) of the SC/FM plays an important role in the effect of the magnetic layers
on Tc: it first increases the area of the interface, which gives stronger proximity effect
and, second, enhances the effect of the stray field on Tc based upon nano-scale
observations of interfaces topography. It was found that the parameter which determines
the effect of magnetic layers on the superconducting layers is not an absolute number of
roughness only, but the ratio of the roughness and the thickness (δ=R/dCo) of the
magnetic layers. On the other hand, these observations invite to elucidate the crystalline
defect structure at the Nb/Co interfaces, namely misfit-compensating dislocations
density, and the associated strain fields to allow localized coherency at the interfaces.
40

ORAL CONTRIBUTIONS
Magnetoresistance oscillations in mesoscopic superconductors*
Francois Peeters
Department of Physics, University of Antwerp, B-2020 Antwerpen, Belgium
Universidade Federal do Ceara, Departamento de Fısica, Fortaleza, Ceara, Brazil
We show in the case of a superconducting Nb ladder that a mesoscopic superconductor
typically exhibits magnetoresistance oscillations whose amplitude and temperature
dependence are different from those stemming from the Little-Parks effect. We
demonstrate that these large resistance oscillations (as well as the monotonic
background on which they are superimposed) are due to current-excited moving
vortices, where the applied current in competition with the oscillating Meissner currents
imposes or removes the barriers for vortex motion in an increasing magnetic field.
Because of the ever present current in transport measurements, this effect should be
considered in parallel with the Little-Parks effect in low-critical temperature (T c )
samples, as well as with recently proposed thermal activation of dissipative vortexantivortex
pairs in high-T c samples
*Work done in collaboration with: G.R. Berdiyorov, M.V. Milosevic, M.L. Latimer,
Z.L. Xiao, W.K. Kwok
41

Inter-band interactions between vortices in multi-band
superconductors
A. Chaves 1 , Davi S. Dantas 1 , M. V. Milošević 2, 1 , G. A. Farias 1 and F. M. Peeters 2, 1
1 Departamento de Física, Universidade Federal do Ceará Caixa Postal 6030, 60455-900,
Fortaleza, Ceara, Brasil.
2 Departement Fysica, Universiteit Antwerpen (Campus Groenenborger) Groenenborgerlaan
171 B-2020Antwerpen, Belgium
The interest in the study of the interaction between vortices in superconductors has been
recently renewed after the experimental observation [1] of unusual vortex lattices in
two-band superconductors, specifically MgB 2 , which was interpreted as being a
consequence of a non-monotonic interaction between vortices. In this case, the
existence of two superconducting bands allows vortices to exhibit features of both type-
I superconductivity (vortex-vortex attraction), at long range, and type-II
superconductivity (vortex-vortex repulsion), at short range, [2] a phenomenom that has
been named type-1.5 superconductivity. Recent theoretical papers [3] have
demonstrated that even more interesting vortex interactions are expected in three-band
superconductors, where, depending on the sign of the inter-band coupling parameters, a
frustration between the phase locking tendencies of the order parameters occurs, leading
to non-composite vortex structures and topological solitons.
In this work, we extend the set of constrained Ginzburg-Landau (GL) equations
developed in Ref. [4] for the study of the interaction between noncomposite vortices in
two- and three-band superconductors. In the former case, our results demonstrate that
the inter-band vortex-vortex interaction potential is monotonically increasing and does
not saturate as the vortices in different bands are further separated. This has an
important effect e.g. on the possibility of dissociation of a composite vortex in the fluxflow
state, predicted by a recent paper. [5] In the three-bands case, we use our method
to obtain the interaction potential governing the separation between vortices in different
bands when noncomposite vortices are formed as a consequence of the frustration.
[1] V. V. Moshchalkov, et al., Phys. Rev. Lett. 102, 117001 (2009).
[2] E. Babaev and M. Speight, Phys. Rev. B 72, 180502(R) (2005).
[3] J. Garaud, et al., Phys. Rev. Lett. 107, 197001 (2011).
[4] A. Chaves, et al., Phys. Rev. B 83, 214523 (2011).
[5] S. Z. Lin and L. N. Bulaevskii arxiv:1208.1964
42

ORAL CONTRIBUTIONS
Study of the multiple gap phenomena in the cuprate and iron-based
high temperature superconductors.
Rustem Khasanov
Paul Scherrer Institut, Switzerland
The application of muSR technique to study the effects of multiple gaps on the
superfluid density is planned to be discussed. The particular attention is planned to be
paid to the coexistence of the superconducting and the pseudogap in Bi2201 family of
cuprate high-temperature superconductors (HTS). The presence of multiple
superconduting gaps will be discussed for the case of the iron based HTS.
43

Research possibilities at the NIST Center for Neutron Research
Juscelino B. Leão
1 NIST Center for Neutron Research, National Institute of Standards and Technology,
Gaithersburg, MD 20899, USA
The NIST Center for Neutron Research (NCNR) is part of the National Institute of
Standards and Technology (NIST) in Gaithersburg, Maryland, USA. Its activities focus
on providing neutron measurement capabilities to the research community. It is a
national center for research using thermal and cold neutrons, offering a number of
neutron instruments for use by all qualified applicants. The “cold” neutron instruments
at NCNR rely on intense beams of neutrons emanating from an advanced liquid
hydrogen moderator. In partnership with the National Science Foundation (NSF), NIST
co-fund the Center for High Resolution Neutron Scattering (CHRNS) that operates six
of the world's most advanced instruments. Time on CHRNS instruments is made
available through a peer-reviewed proposal system. Some access to beam time for
collaborative measurements with the NIST science staff allows for international
research collaboration.
An introduction to the capabilities available at the NCNR, along with a few
exemplary results relevant to superconductivity and magnetism under extreme
conditions will be presented.
44

ORAL CONTRIBUTIONS
The evolution of superconductivity in the ternary AnM3n-1B2n
(n=1:A= Ca, Sr; M=Rh, Ir and n=3:A= Ca, Sr; M=Rh) phases
M. ElMassalami
Instituto de Física, Universidade Federal do Rio de Janeiro, Caixa Postal 68528, 21941-972
Rio de Janeiro, Brazil
We present our work on the search for superconductivity in the titled homologous
series. We followed the evolution of the metallic properties of this series when n as well
as the atomic type of A and M are varied, covering the range: for n=1: A= Ca, Sr and
M=Rh, Ir while for n=3: A= Ca, Sr and M=Rh. The crystal structure of n =1 members is
known from previous studies to be the CaRh 2 B 2 -type (Fddd) while that of n =3 is the
Ca 3 Rh 8 B 6 -type (Fmmm): the later can be visualized as a stacking of structural fragments
from AM 3 B 2 and AM 2 B 2 . It is observed that the metallic properties of the n=1 and 3
members are distinctly di¤erent: on the one hand, the n=1 family exhibits linear coe¢
cient of the electronic specific heat γ≈3 mJ/molK 2 , Debye temperature Θ D ≈300 K, a
normal conductivity down to 2 K, and a relatively strong linear magnetoresistivity for
.elds up to 150 kOe. The n=3 family, on the other hand, exhibits γ≈18 mJ/molK 2 , ΘD ≈
330 K, a weak linear magnetoresistivity, and an onset of superconductivity (for
Ca 3 Rh 8 B 6 , Tc=4.0 K and H c2 = 14.5 kOe while for Sr 3 Rh 8 B 6 , Tc=3.4 K and H c2 ≈ 4.0
kOe). To understand these remarkable differences, we carried out electronic band
structure calculation. Indeed, the difference among the electronic properties of these two
families are found to be related to the distinctly different electronic band structures and
densities of states, DOS, N(E). In particular, the Fermi level, E F of Ca 3 Rh 8 B 6 lies at
almost the top of a DOS peak while that of CaRh2B2 lies at a bottom of a local valley.
Based on these results, we attributed the superconductivity of A 3 Rh 8 B 6 to the presence
of a pronounced local peak in the DOS curve. Furthermore, we observed that though all
atoms contribute to this peak, however the contribution of the Rh atoms (in particular at
the 16j sites) is the strongest. We found a satisfactorily agreement between the
measured and calculated γ.
45

Magnetic and Superconductor properties of RuSr2GdCu2O8 -type
Ruthenocuprates
L.T. Corredor 1 , J. Albino Aguiar 2 , J. Roa-Rojas 2 , D.A. Landínez Téllez 2 , P. Pureur 3 , F.
Mesquita 3
1
Departamento de Física, Universidade Federal de Pernambuco, 50670-901, Recife-PE, Brasil.
2
Grupo de Física de Nuevos Materiales, Departamento de FísicaUniversidad Nacional de
Colombia, Bogot´a D.C., Colombia.
3
Instituto de Física, Universidade Federal do Rio Grande do Sul, Porto Alegre-RS, Brasil
The discovery of superconductivity in the ruthenocuprates RuSr 2 GdCu 2 O 8 (Ru-1212)
and RuSr 2 (R 1+x Ce 1−x )Cu 2 O 10 (R=Sm, Eu and Gd) by Bauernfeind et.al. in 1995, and the
report, two years later, by Felner et.al. of the coexistence of superconductivity and
magnetism in these compounds, renewed the attention of both theoretician and
experimentalist scientists, for the study of the interplay of superconductivity and
magnetism. The outstanding characteristic of these compounds over other magnetic
superconductors like Chevrel phases or rare earth ternary borides is the fact that the
magnetic transition temperature is much higher than critical superconducting
temperature, turning them unique materials. However, these compounds are extremely
sensitive to synthesis process, difficulting their study. With the aim of reducing the
synthesis dependent characteristics, it was developed a route for the ruthenocuprates
production involving the production of double perovskites Sr 2 LnRuO 6 (Ln=lanthanide)
as precursor oxides. We have performed a study of the structural, transport, and
magnetic properties of polycrystalline samples of the rhenium-doped ruthenocuprate
Ru 1−x Re x Sr 2 GdCu 2 O y (x=0.00, 0.03, 0.06, 009, 0.12). The samples were prepared by a
two-step solid-state reaction procedure, including the synthesis of the double perovskite
Sr 2 GdRu 1−x Re x O y . Magnetic characterization revealed the ferromagnetic character of
the samples, with transition temperatures between 135-155K, and absence of Meissner
state. The first three samples (x=0.00-0.06) show a non-zero transition in resistivity,
with transition temperatures between 21-41K, while the x=0.09-0.12 samples show a
semiconductor type behavior. This transition is shifted to lower temperatures by applied
magnetic field, keeping its behavior under fields up to 1 T. It is evidenced a granularity
effect in the broadening of ρ(T) curves in applied field. Magnetoresistivity
measurements show positive values for temperatures above the magnetic transition, and
slightly negative values below, without appreciable variation even for high applied
magnetic fields. The Re doping effect on the Ru-1212 superconducting and magnetic
properties are discussed.
This work was partially supported by the Colombian agencies Colciencias, the
Division of Investigations, Universidad Nacional de Colombia (DIB - Bogot); and
Brazilian CNPq, CAPES and FACEPE (APQ-0589-1.05/08).
46

ORAL CONTRIBUTIONS
Emergence of superconductivity from magnetic order in correlated
electron materials
M. Brian Maple
Department of Physics University of California, San Diego, La Jolla, CA 92093 USA.
Multinary compounds based on transition metal, rare earth, and actinide elements in
which the localized d- and f-electron states are admixed with conduction electron states
provide a wealth of correlated electron phenomena: e.g., metal-insulator transitions,
colossal magnetoresistance, valence fluctuations, hybridization gap semiconductivity,
heavy fermion behavior, non-Fermi liquid behavior, unconventional superconductivity,
magnetic order, quadrupolar order, etc. The occurrence of such a wide range of
correlated electron phenomena arises from a delicate interplay between competing
interactions that can be tuned by variation of an external control parameter δ such as
chemical composition x, pressure P, or magnetic field H, resulting in complex
temperature T vs x, P, and H phase diagrams. A particularly striking phenomenon that
has been observed in many correlated electron systems, including heavy fermion
felectron compounds, high Tc superconducting cuprates, and, more recently, many Febased
materials, is the emergence of superconductivity near the critical value δcr of a
control parameter (usually, xcr or Pcr) where a magnetically ordered phase is
suppressed to 0 K. For some systems, the Fermi liquid paradigm is found to be violated
in the vicinity of δcr, which is manifested as weak power law and logarithmic
divergences in the physical properties at low temperature (so called non-Fermi liquid
behavior). The superconductivity and the non-Fermi liquid behavior may be due to
quantum fluctuations of the magnetic order parameter (OP) associated with the
suppression of a second order magnetic phase transition to 0 K at δcr, where δcr is
referred to as a quantum critical point (QCP). The formation of the superconducting
phase appears to “protect” the QCP by removing the degeneracy associated with the OP
fluctuations, and the superconducting electron pairing is apparently mediated by
magnetic interactions. In contrast, magnetic interactions generally have a destructive
effect on conventional BCS superconductivity. Interestingly, superconductivity has
recently been found to emerge from charge ordered phases such as charge density
waves. In this talk, we describe selected experiments, some of which have been carried
out in our laboratory, that address the interrelation between superconductivity, spin and
charge order, and non-Fermi liquid behavior in novel d- and f-electron materials. The
support of the US NNSA, DOE, AFOSR and NSF is gratefully acknowledged.
47

Fine tuning of the ground state of CaFe 2 As 2 : Pressure, doping, and
nanoscale precipitates
.
Sergey L. Bud’ko
Ames Laboratory, US DOE and Department of Physics and Astronomy, Iowa State University,
Ames, Iowa, 50011, USA
I will present an overview of our recent results on a remarkable large response of
CaFe 2 As 2 and Ca(Fe 1-x Co x ) 2 As 2 single crystals grown from excess FeAs to annealing
and quenching temperatures. 1,2 By combination of doping and annealing/quenching, the
system can be tuned to low temperature AFM-orthorhombic, superconducting, or nonmagnetic
collapsed tetragonal state, all at ambient pressure. 3D, x – T anneal – T, phase
diagram with x and T anneal as two independent parameters is obtained. TEM results
suggest that semi-uniform distribution of nano-precipitates in quenched samples causes
a strain field that affects the system similarly to external, physical pressure. 3
- This work was supported by the US Department of Energy, Office of Basic Energy
Science, Division of Materials Sciences and Engineering. The Ames Laboratory is
operated for the US Department of Energy by Iowa State University under Contract No.
DE-AC02-07CH11358.
1. S. Ran, S. L. Bud’ko, D. K. Pratt, A. Kreyssig, M. G. Kim, M. J. Kramer, D. H.
Ryan, W. N. Rowan-Weetaluktuk, Y. Furukawa, B. Roy, A. I. Goldman, and P. C.
Canfield, Phys. Rev. B 83, 144517 (2011).
2. S. Ran, S. L. Bud’ko, W. E. Straszheim, J. Soh, M. G. Kim, A. Kreyssig, A. I.
Goldman, and P. C. Canfield, Phys. Rev. B 85, 224528 (2012).
3. E. Gati, S. Köhler, D. Guterding, B. Wolf, S. Knöner, S. Ran, S. L. Bud'ko, P.C.
Canfield, M. Lang, arXiv:1210.5398 (2012)..
48

ORAL CONTRIBUTIONS
Superconductivity and Quantum Criticality in Heavy Fermions
Z. Fisk
UC Irvine
Superconductivity provides an alternate to magnetic order for removing entropy from
the electronic system at low temperature in heavy Fermion materials. This heavy
Fermion superconductivity is very generally found in the vicinity of a quantum critical
point, and we discuss the 115 class of superconductors from this dual viewpoint and its
relevance to other classes of superconductors.
.
49

Field induced superconductivity, dipolar clusters and ferroelectricity
in high Tc superconductors
F. V. Kusmartsev 1 , M. Saarela 2
1 Department of Physics, Loughborough University, LE11 3TU, UK
2 Department of Physics, P.O. Box 3000, FIN-90014, University of Oulu, Finland
We show that charge carriers doping induces a formation of electric dipolar moments in
cuprates. A single dipole moment is created between the dopant ion and a bound cluster
of holes in the CuO plane. The binding energy of the cluster de_nes the pseudo-gap.
Such dipoles may form a disordered state of dipolar glass or an ordered state such as
stripes, that depends on the preparation of the sample. The lowest energy of the ordered
system corresponds to a local anti-ferroelectric ordering in the CuO plane. The electric
dipoles are strongly interacting with electromagnetic radiation. The usual mobility of
dipoles is very low. When a sample is subjected to an electromagnetic radiation it
changes signi_cantly. This leads to a fractal growth of dipolar clusters. The existence of
electrical dipoles reveals a series of a new phenomena such as ferroelectricity, a strong
light and a microwave absorption as well as _eld induced superconductivity.
50

ORAL CONTRIBUTIONS
From superconductivity to the Higgs Boson
Eduardo C. Marino
Instituto de Física - UFRJ
The similarities between the Higgs mechanism of the Standard Model of the
fundamental interactions and the Meissner effect of Superconductivity are investigated
and reviewed. We also describe the common features of the Yukawa mechanism of
mass generation to matter particles and the Peierls mechanism of energy gap generation
in polymers. The identification of similar mechanisms operating in apparently
uncorrelated physical phenomena shows the beauty and unity of Physics and is a source
of inspiration for new ideas.
51

Magnetic cloaking and concentration with ferromagneticsuperconducting
hybrids.
Carles Navau, Alvaro Sanchez, Jordi Prat-Camps
Departamento de Física, Universitat Autnoma de Barcelona.
We present some recent advances in the design of systems that combine
superconducting and ferromagnetic features to achieve global properties that cannot be
achieved with these materials individually. The mathematical background of the designs
is based on the trasformation optics technique, that will be reviewed. From this
technique we present devices able to cloak an external magnetic feld or, oppositely, to
concentrate that field up to unprecendent densities in a given interior region of the
system. We present how ferromagnetic-superconducting hybrid systems are excellent
candidates to fabricate these devices since they combine opposite effects (expulsion and
concentration of magnetic fields) that can be tuned adequately to yield the desired
properties. We shall also present the experimental verification of the cloaking effects
with one of these systems.
52

ORAL CONTRIBUTIONS
Investigation of the nature of artificial pinning centres in
nanostructured superconducting films in correlation with the bulk
pinning force
Adrian Crisan
School of Metallurgy and Materials, University of Birmingham, B15 2TT U.K.
E-mail: I.A.Crisan@bham.ac.uk
For practical applications of superconducting materials in applied magnetic fields,
artificial pinning centres in addition to natural ones are required to oppose the Lorentz
force. These pinning centres are actually various types of defects in the superconductor
matrix. The pinning centres can be categorised on their dimension, volume, surface or
point and on their character, normal cores or Δκ cores. Dew Hughes formula will
determine the type of pinning centres present in a sample using the general formula
, where p and q depend on the type of pinning centres. Different samples
have been investigated, with various thicknesses, temperatures and nanostructured
additions to the superconducting matrix. Results show that normal surface pinning
centres are present throughout almost all the samples, as dominant pinning mechanism.
Such 2D extended pinning centres are mainly due to dislocations, grain boundaries,
nanorods. Strong normal point pinning centres were found to be common in BZO doped
YBCO samples. All other types of pinning centres, in various (minor) concentrations
were found in some of the samples. The results were correlated with TEM images of
various defects in the nanostructured superconductors.
53

Flux fractionalization and flux dynamics in two-band superconductors
M.V. Milošević *
Universiteit Antwerpen, Belgium and UFC, Brazil
In this talk, I will review our recent findings on fractional vortex states and their
dynamics in mesoscopic two-band superconductors. The main underlining mechanism
for the observed flux fractionalization is the difference in lengthscales for the two
electronic condensates in a two-band sample [1], which is particularly enhanced close to
the hidden critical point [2], the temperature at which one of the bands becomes
passive. Such difference in lengthscales leads to different interaction of two condensates
with the sample boundaries and defects, which becomes apparent in the stationary
vortex structure, but also causes yet unobserved dynamics of vortices [3], each
separated in two fractions, of different size, and different ‘viscosity’ of the host
condensate for the given applied current.
Finally, I will also address the issue of interaction of the currents in the two
condensates. This so-called ‘drag’ effect can act against the direct coupling between the
condensates and cause breakup of vortices even if the relevant lengthscales are not in
competition [4]. This is particularly the case in the dirty limit, characteristic of
experimentally deposited thin film samples. Hence we predict an observable doubling of
the Abrikosov vortex lattice in such films.
Email address: milorad.milosevic@ua.ac.be
References
[1] R. Geurts, M.V. Milošević, and F.M. Peeters, Phys. Rev. B 81, 214514 (2010); J.C.
Piña, C.C. de Souza Silva, and M.V. Milošević, Phys. Rev. B 86, 024512 (2012).
[2] L. Komendová, Y. Chen, A.A. Shanenko, M.V. Milošević, and F.M. Peeters, Phys.
Rev. Lett. 108, 207002 (2012).
[3,4] Articles in preparation.
54

ORAL CONTRIBUTIONS
Stabilizing fractional vortex states in two-band superconductors with
mesoscopic magnetic textures
JuanC.Piña 1 , Clécio C.de Souza Silva 1 , Milorad Milosevic 2
1 Departamento de Física,Universidade Federal de Pernambuco,50670-901,Recife­PE, Brazil
2 Departement Fysica, Universiteit Antwerpen ,Groenenborgerlaan 171, B-­-2020 Antwerpen,
Belgium
Many properties of a macroscopic quantum condensate can be unveiled by rotating it
and studying the structure of the induced quantized vortices. In particular, the amount of
magnetic flux carried by vortices in conventional superconductors determines whether
the material is of type I or type II. In the first case, vortices tend to merge into large flux
domains carrying many flux quanta. Conversely, for the type-II material, vortices are
singly quantized and repel each other. However, some superconductors, the recently
discovere MgB2 and iron-pnictides included, are provided with two or more electronic
condensates arising from Cooper pairing indifferent bands of the material. These
multiband systems have attracted much interest in the last decade because they exhibit a
variety of new and interesting phenomena with no counterpart in conventional singlecomponent
superconductors. Perhaps the most intriguing of these phenomena are
related to the exotic vortex structures that can emerge in a multi component
superconductor [1].
In this work, we investigate the stability of non composite fractional vortex
states in a mesoscopic two-band superconductor within the two-component Ginzburg
Landau model. Our analysis explicitly takes into account the relationship between the
model parameters and microscopic material parameters, such as partial density of states,
Fermi velocities and elements of the electron-phonon coupling matrix. Previous studies
have shown that a mesoscopic two­band superconductor can stabilize vortexstructures
containing different winding number in each band (L1.L2 and fractional flux [2,3].
However, such states are restricted to very low values other interband coupling constant.
We propose an efficient way of increasing the range of parameters for which these
fractional vortex states can be stabilized [4]. In particular, our proposal allows for the
observation of fractional vortex structures in materials with stronger coupling, where
those states are forbidden at a homogeneous field. This is accomplished with the help of
the stray fields of a suitably prepared magnetic dot placed nearby the superconducting
disk. Our G-L calculations demonstrate that, depending upon its magnetic moment (m)
orientation, the dot can act as both a trap to enhance the stability of fractional states
(m//H) or a magnifying lens splitting up the otherwise compact vortex configuration.
The later property is interesting for experimental visualization of such states but at the
expenses of better stability.
[1] E Babaev, Phys. Rev. Lett. 89, 06700 (2002).
[2] L.F. Chibotaru and V.H. Dao, Phys.Rev.B 81, 020502(R) (2010).
[3] R. Geurts, M. V. Milosevican, F. M. Peeters, Phys. Rev. 81, 21451 (2010).
[4] J. C. Piña, C.C.dSouzaSilva, and M. V. Miloševic, Phys. Rev. 86, 024512 (2012).
55

Unusual thermoelectric properties of the quasi-one-dimensional metal,
Li 0:9 Mo 6 O 17
*
Joshua L. Cohn 1 , C. A. M. dos Santos 2 , J. J. Neumeier 3
1 Department of Physics, University of Miami, Coral Gables, FL 33124.
2 Escola de Engenharia de Lorena - USP, P. O. Box 116, Lorena-SP, 12602-810, Brazil.
3 Department of Physics, Montana State University, Bozeman, Montana 59717.
Li 0:9 Mo 6 O 17 (‘lithium purple bronze” or LiPB) is a highly anisotropic, low-temperature
superconductor (Tc = 2 K) with many unusual properties. Photoemission1 and
tunneling2 studies suggest that the conducting Mo-O chains of this compound constitute
a Luttinger liquid. A giant Nernst effect is observed in the normal state,3 and
measurements of upper critical fields suggest that the superconducting state may be
characterized by triplet pairing.4 To further characterize the normal state behavior, we
will present our recent measurements of electrical resistivity (ρ) and thermo-electric
power (S) transverse to the conducting chains (crystallographic c axis) on single-crystal
LiPB. While ρc(T) exhibits metallic behavior at T ≤ Tmax ≈ 270 K, it decreases with
increasing T above this temperature similar to the behavior of ½ transverse to the
conducting planes or chains in a variety of low-dimensional metals.5;6 The
corresponding thermopower, Sc, which is relatively T-independent and a modest 30
µV/K at low T, increases sharply with increasing T near Tmax, and exceeds 200 µV/K
at T > 400 K. The role of tunneling through interchain defect states will be discussed.
* Work supported by the U.S. Department of Energy O±ce of Basic Energy Sciences
(DE-FG02-12ER46888, Univ. Miami), the National Science Foundation (DMR-
0907036, Mont. St. Univ.), and in Lorena by the CNPq (301334/2007-2) and FAPESP
(2009/14524-6).
[1] F. Wang et al., Phys. Rev. Lett. 96, 196403 (2006).
[2] J. Hager et al., Phys. Rev. Lett. 95, 186402 (2005).
[3] J. L. Cohn et al., Phys. Rev. Lett. 108, 056604 (2012).
[4] J.-F. Mercure et al., Phys. Rev. Lett. 108, 187003 (2012).
[5] D. B. Gutman and D. L. Maslov, Phys. Rev. B 77, 036115 (2
56

ORAL CONTRIBUTIONS
A structural phase transition in V, Nb and Ta and the possible
importance for A15 superconductors
John J. Neumeier 1 , R. K. Bollinger 1 , B. D. White 1 , S. Francoual 2 , C. A. M. dos Santos 3 , H. R. Z.
Sandim 3 , Y. Suzuki 4 , R. Avci 1 , M. von Zimmerman 2 , A. Migliori 4 , and J. B. Betts 4
1 Physics Department, Montana State University, Box 173840, Bozeman, MT, 59717, USA.
2 HASYLAB at DESY, Notkestr. 85, D22607, Hamburg, Germany.
3 Escola de Engenharia de Lorena – USP, PO Box 116, LorenaSP, 12602810, Brazil.
4 National High Magnetic Field Laboratory, Los Alamos National Laboratory, Los Alamos, NM,
87545 USA.
The 5d elements V, Nb and Ta are generally thought to possess cubic crystal structures.
Recently, we observed a structural phase transition using high resolution thermal
expansion between room temperature and absolute zero in all three of these elements.
Its magnitude is small, as reflected in a relative length change along the three principal
cubic axes that differs by about 1 part in 10 3 or less. It is extremely broad and hysteretic
and sensitive to impurities. We have characterized it as martensitic, although the
low‐temperature crystal structure remains unknown and competition between the two
structures needs to be directly observed. A‐15 superconductors containing V and Nb are
also known to exhibit martensitic structural phase transitions. In A‐15 compounds, the
structural phase transitions occur near to the superconducting phase transitions, and
were thought to play an important role in superconductivity. Published work on A‐15s
will be reviewed, and discussed in the framework of our observations in the elements.
57

POSTER CONTRIBUTIONS
ABSTRACTS
POSTERS CONTRIBUTIONS
58

Superconducting BSCCO pellets and wires prepared with
nanoparticulated calcium compounds
Natacha A. Nogueira, Dayse I. dos Santos
Grupo Mav/LMSCN - Pós Graduação em Ciência dos Materiais Universidade Estadual
Paulista - Campus de Bauru, Brazil.
BSCCO pellets were prepared by melt-texturing with the addition of fine particles of
calcium compounds. The microstructural analysis showed that, despite the
predominance of the 2212 phase for all observed X-ray diffractions, there were
significant changes in the texture of the ceramic and in the magnetization depending on
the added compound. Based on these experiments, two types of superconducting
BSCCO PIT wires were prepared: 1 wt. % of calcium silicate addition and 1 wt. %
calcium zirconate addition, as well as the reference one. The microstructure and its
superconducting magnetization and transport properties will be investigated after
appropriate heat treatment. The magnetization curves as a function of applied magnetic
field obtained for pellets indicated the existence of different mechanisms for improving
the critical current density of each wire. It is expected that the properties obtained for
the modified superconducting wires may complete the pellet results and help to find out
if the main factor for the improvement of the critical current density is the creation of
new pinning centers or the increase of grains alignment and texturing in the material due
to the addition of the calcium compounds.
59

POSTER CONTRIBUTIONS
Processing and Characterization of Melt-textured Y 1-x Pr x Ba 2 Cu 3 O 7-δ
and [YBa 2 Cu 3 O 7-d ] 1-x [PrBa 2 Cu 3 O 7-d ] x Superconductor
Yuri Aparecido Opata, Lincoln Brum Leite Gusmão Pinheiro, Joao Frederico Haas Leandro
Monteiro, Simone Aparecida Silva, Pedro Rodrigues Jr., Alcione Roberto Jurelo
Department of Physics, Universidade Estadual de Ponta Grossa,Campus Uvaranas - Av.
General Carlos Cavalcanti, 4748 - CEP 84030-900, Campus Central - Praça Santos Andrade,
Ponta Grossa – Paraná, Brazil
e-mail: yuriopata@gmail.com
We report the processing and characterization of top-seeded melt-textured (TSMT) Y1-
xPrxBa2Cu3O7-δ (YPr-123) and [YBa2Cu3O7-d]1-x[PrBa2Cu3O7-d]x (Y/Pr-123), for
x = 0.00 and 0.05. These stoichiometries were chosen for the analysis of the Pr doping
effect on the mechanical properties and critical phenomena. First, we prepared
Nd1.8Ba2.4Cu3.4Oy seeds using NdBa2Cu3Ox and Nd4Ba2Cu2Ox powders. These
two phases were sintered twice at 900 and 1100 °C for 24 h, respectively, and mixed to
have the composition Nd1.8Ba2.4Cu3.4Ox. The seeds precursors were pressed in
pellets, heated at 1136 °C in 2 h and held for 3 h, then rapidly cooled to 1096 °C in 6
min, and slowly cooled to 950 °C in a rate of 1 °C/h. After, we prepared Y1-
xPrxBa2Cu3O7-δ phase, which was calcined in 880, 900 and 920 °C, respectively. The
Y2BaCuO5 (Y-211) and YPr-123 phases were grinded and mixed in proportion 75 %
wt. YPr-123 + 25 % wt. Y-211 + 1 % wt. CeO and pressed in pellets. These samples
were sintered in 920° C for 24 h, heated the 1045° C for 3 h, quickly cooled at 1005 °C
and slowly cooled at 990 °C in 30 h. For the Y/Pr-123 we prepared theYBa2Cu3O7-δ
(Y-123) and PrBa2Cu3O7-δ (Pr-123) phases, these were calcined with the same
temperatures used in the Y/Pr-123. The compounds were mixed in the proportion 75 %
wt. [95 % wt. Y-123 + 5 % wt. Pr-123] + 25 % wt. Y-211 + 1 % wt. CeO. The
successful top-seeded melttextured samples were characterized by X-ray diffraction,
optical microscopy, scanning electron microscopy, resistivity measurements and
mechanical properties by instrumented indentation and conventional Vickers
measurements. To identify power-law divergences of the conductivity, the resistivity
data were analyzed in terms of the temperature derivative of the resistivity and of the
logarithmic temperature derivative of the conductivity.
60

Fluctuation-induced conductivity and phase separation in composite
samples (YBa 2 Cu 3 O 7-d ) 1-y -(PrBa 2 Cu 3 O 7-d ) y
João Frederico Haas Leandro Monteiro 1 *, Yuri Aparecido Opata 1 , Simone Aparecida da Silva 1 ,
Pedro Rodrigues Júnior 1 , Alcione Roberto Jurelo 1 , Lincoln Brum de Leite Gusmão Pinheiro 2
Departamento de Física, Universidade Estadual de Ponta Grossa, Av. Gen. Carlos Cavalcanti
4748, 84.030-000, Ponta Grossa, Paraná, Brazil.
Instituto Federal de Educação, Ciência e Tecnologia do Rio Grande do Sul, Rua Domingos
Zanella 104, 99.700-000, Erechim, Rio Grande do Sul, Brazil.
Fluctuation-induced conductivity in composite samples (YBa 2 Cu 3 O 7-d ) 1-y -(PrBa 2 Cu 3 O 7-
d) y was investigated. The samples with 0 ≤ y ≤ 0.1 were produced through the solid state
reaction method. Powder X-ray Rietveld analysis for the composites demonstrated that
the patterns are identical to that of YBa 2 Cu 3 O 7-d . Measured of the magnetization
confirmed the values to critic temperature obtained by measured of the electrical
transport. From the critical exponent analysis, it could be observed that the transport
properties of composites are governed by the presence of two phases: YBa 2 Cu 3 O 7-d and
PrBa 2 Cu 3 O 7-d . Splitting of the pairing transition was observed and two critical
temperatures were identified, but only one is strongly affected by Pr. The composite
structure can be thought as a three-dimensional grain percolation system with the
structure of Pr-grain and Y-grain unit cell. Posteriorly, we produced composite samples
(YBa 2 Cu 3 O 7-d ) 0.95 -(PrBa 2 Cu 3 O7-d) 0.05 doped with Ag in order to ensure that both
transition are only related with the phases YBa 2 Cu 3 O 7-d and PrBa 2 Cu 3 O 7-d since the Ag
penetrate in the regions intergrains. The results shown that with the increase of Ag the
peak of the granularity disappeared, but the peaks of phases YBCO and PBCO remained
unchanged.
*e-mail: jfhlmonteiro@hotmail.com
61

POSTER CONTRIBUTIONS
London Approximation in a Nematic-Superconductor State
Rafael de Vasconcellos Clarim, Daniel G. Barci
Universidade do Estado do Rio de Janeiro, RJ, Brazil
A series of experiments [1] in the cuprate superconductor La 2−x Ba x CuO 4 [2] have shown
that it exhibits a remarkable dynamical layer decoupling behavior near the x = 1/8
”anomaly”. This case can be naturally understood by postulating that the
superconductor (SC) order becomes ”striped”. Similar effects have been seen in
stripeordered La 1.6−x Nd 0.4 Sr x CuO 4 and in the magnetic-field induced stripe-ordered
phase of La 2−x Sr x CuO 4 . In the striped SC state, a pair-density-wave (PDW), the SC pair
field oscillates in space with an ordering wave vector. One of us, have studied a detailed
phase diagram that this proposal implies [3]. One of its consequences is that, the thermal
melting of a PDW state produces a novel uniform 4e-superconductor state (4e-SC) that
has also nematic (orientational) order.
In this present work, we have built a Ginzburg-Landau theory in two dimensions
for this state called “Nematic Superconductor” [4], with two order parameters: the
complex SC and the nematic order parameter given by a traceless symmetric tensor.
Rotational as well as gauge invariance force a geometrical coupling between the two
order parameters.
In order to minimize the free energy, the current should be locally perpendicular
to the director n. We find two types of topological configurations that minimize the free
energy: a) isolated disclinations, and b) (half) vortices bounded to disclinations.
Vortices and disclinations have an attractive logarithmic interaction, whose sign is
independent of the sign of their topological charges. Therefore, in the regime where the
superconductor density is not small (London Approximation) the disordering of N-SC
can only be produced in two ways: a) by unbinding disclinations, which restores
isotropy but does not affect the SC (the N-SC/SC transition), or b) by the proliferation
of (half) vortices tightly bound to disclinations (the N-SC/normal transition).
This work has financial support from the sponsoring agency FAPERJ.
[1] E. Berg, E. Fradkin, and S. A. Kivelson, Nature Physics 5, 830 (2009).
[2] Q. Li et al., Phys. Rev. Lett.99, 067001 (2007); J. M. Tranquada et al., Phys. Rev.
B78,174529 (2008).
[3] Daniel G. Barci, Eduardo Fradkin, preprint arXiv:1005.1928 , accepted for
publication in PRB-Rapid
Communications, (2011).
[4] R. Clarim, Teoria de Landau-Ginzburg para o Estado Supercondutor Nemático,
UERJ, 2012
62

Effect of oxygen-content on the tribo-mechanical properties of single
crystals YBa 2 Cu 3 O 7-d superconductor
Simone Aparecida da Silva, Alcione Roberto Jurelo, Carlos Eugênio Foerster, Francisco Carlos
Serbena, Gelson Biscaia de Souza.
Departamento de Física, Universidade Estadual de Ponta Grossa, Av. Gen. Carlos Cavalcanti
4748, 84.030-000, Ponta Grossa, Paraná, Brasil
The influence of the oxygen-content on the tribological and mechanical properties of
single crystals YBa 2 Cu 3 O 7-d superconductor was studied. The growth of large and high
quality YBa 2 Cu 3 O 7-d superconductor was obtained by the self-flux method. Some single
crystals were submitted to oxygenation in a controlled O 2 atmosphere during 10 days at
the temperature 400 °C. Samples were characterized by scanning electron microscopy
(SEM), atomic force microscopy (AFM), X-ray diffraction (XRD) and magnetization
measurements. The mechanical properties (elastic modulus and hardness) were
determined by the instrumented indentation technique on the ab- and the a(b)c-planes of
the single crystals, with applying loads ranging from 10 to 400 mN using a Berkovich
indenter. The scratch resistance in both planes was studied using the same instrumented
indentation equipment with ramping load up to 200 mN. The magnetization
measurements showed that the sample oxygenated transition normal-superconducting
occurs at a temperature of 92.7 K. Prior to oxygenation, the elastic modulus and
hardness values in the ab-plane were 50.4 GPa and 5.3 GPa, respectively. For the a(b)cplane,
the values for the elastic modulus and hardness were 74.4 GPa and 3.7 GPa,
respectively. After the oxygenation process, the single crystals presented increased
hardness values for both planes, however an intensive embrittlement were also verified.
The material´s plastic deformation under scratching, prior to oxygenation, were
characterized on the ab-plane by the formation of pile-ups in the tip track edges due to
the lamellae cracking; on the other hand, the a(b)c-plane presented debris release from
the groove and cracks inside it. Likewise, the scratch behavior after the oxygenation
were predominantly brittle for both ab- and a(b)c-planes, with intense debris release. In
conclusion, the oxygenation process intensifies the brittle behavior of YBa2Cu3O7-
single crystals.
Keywords: superconductor, single crystals, mechanical properties, tribological properties.
63

POSTER CONTRIBUTIONS
Processing and characterization of YBa 2 Cu 3 O 7-x thick films using
electrodeposition
Thiago Luís Schneider 1 , Pedro Rodrigues Jr. 1 , Jarem Raul Garcia 2
1 Departamento de Física Universidade Estadual de Ponta Grossa, Ponta Grossa, Paraná,
Brazil.
2 Departamento de Química, Universidade Estadual de Ponta Grossa, Ponta Grossa, Paraná,
Brazil.
The applications of the superconducting materials require, among other characteristics,
homogeneity and easy adaptation to different physical forms. The superconducting
oxides, due to their ceramic nature, have trouble meeting these characteristics. Samples
produced by the method of solid state reaction in general are not homogeneous and
difficult reproducibility. Homogeneous samples in different physical forms can be
obtained as films. The electrodeposition, among the various techniques used to film
growth, is a technique of low cost and easily reproducible. We report the production of
thick films produced with cyclic voltammetry and differential pulse voltammetry.
Solutions of Y(NO 3 ) 3 , Ba(NO 3 ) 2 , Cu(NO 3 ) 2 were prepared in DMSO separately and
subsequently mixed. For cyclic voltammetry scans were conducted from 0 V to -1.6 V
and 0 V to -3.5 V with speeds of 15 mVs-1 and 30 mVs -1 . Measurements of differential
pulse voltammetry were performed with potentials -1 V and -4.5 V with duration of
pulses of 1s and 3s respectively, each one repeated 5 times. The substrates were FTO
and alumina both coated with silver. The films obtained by cyclic voltammetry showed
the best results. These films have a higher homogeneity and better adhesion to the
substrate. The films processed, regardless of the technique used, showed whitish
formations and this was attributed to the formation of barium carbonate. The samples
were characterized by Raman spectroscopy and these results are under analysis.
64

Single crystal growth and characterization of the intermetallic systems
YIn 3 and FeGa 3
M.Cabrera-Baez, E.T.Magnavita, R.A.Ribeiro, L.M.Ferreira, C. Rettori, M.A.Avila
CCNH, Universidade Federal do ABC, 09210-170 Santo André, SP, Brazil
We investigate the structural, thermodynamic, magnetic and transport properties of the
binary intermetallic systems YIn 3 and FeGa 3 , grown as single crystals by the self-flux
technique, aiming at better understanding of the recently reported filamentary
superconductivity in the first, and the emergence of electron doping-induced
ferromagnetism in the second, out of its original diamagnetic semiconducting state. We
present collaborative works exploring ESR on YIn 3 doped with Gd and Mössbauer
spectroscopy in FeGa 3 doped with Ge, Zn.
65

POSTER CONTRIBUTIONS
Superconductivity in the T 2 phase of the Ta 5 Ge 3-x B x
Correa, L.E. 1 ; Fisk, Z. 2 ;Machado, A. J. S. 1 , Nunes , C. A. 1 , Pinto, A.A.A. 1 and Coelho, G. C. 1
1 Escola de Engenharia de Lorena, Universidade de São Paulo, P.O. Box 116, Lorena, SP,
Brasil.
2 Departments of Physics and Astronomy, University of California at Irvine, Irvine, CA 92697,
USA.
In the Ta-Ge system the Ta 5 Ge 3 phase is not superconductor. Considering the high
solubility of this phase for boron, in this work it has been evaluated the effect of boron
doping in Ta 5 Ge 3 on the electrical, heat capacity and magnetic properties of the
produced materials. It has been shown that boron doping promoted superconductivity
for line composition. The Ta 5 Ge 3-x B x , also named T 2 phase, crystallizes in the tetragonal
symmetry with Cr 5 B 3 prototype structure. In this composition the sample presented the
maximum superconducting critical temperature (3.4 K). Others systems that exhibit the
existence of the T 2 phase present superconductivity such as Mo 5 SiB 2 (Tc = 5.5 K),
Nb 5 Si 3-x B x (Tc = 7.8 K) and W 5 SiB 2 (Tc = 5.5 K). The critical temperature depends on
the stoichiometric ratio between Ge and Boron that the phase is the Ta 5 Ge 3-x B x .
66

Synthesis and properties of a new superconducting compound of
ZrNi x S 2 composition.
Scaramussa A. C. 1 ; Fisk Z 2 , Machado A. J. S. 1
1 Escola de Engenharia de Lorena, Universidade de São Paulo, P.O. Box 116, Lorena, SP,
Brazil.
2 Departments of Physics and Astronomy, University of California at Irvine, Irvine, CA 92697,
USA
Since the discovery of superconductivity in chalcogenides in Fe-Se system and in iron
pnictides much attention have been give for synthesis of new materials which can
exhibit superconductivity. Within this context in this work we show results which
suggest that ZrNi x S 2 , where x can assume 0.3, 0.5 and 0.8 values, is a new
superconductor material. This compound crystallizes in a new crystallographic structure
with hexagonal symmetry belongs to the space group R – 32/m. Indeed this compound
is a variation of the Zr 3 S 4 which can be considered as the prototype structure of this new
compound (ZrNi x S 2 ). In this prototype structure zirconium atoms may occupy two
different sites in the structure. Thus, nickel atoms substitute zirconium in a specific site
of the structure. These results suggest that superconducting critical temperature is
dependent of the nickel content in this new compound. The optimum Ni content yield to
Tc ~ 9.8 K.
67

POSTER CONTRIBUTIONS
Superconductivity in a new compound of ZrCuxTe2 stoichiometry
N. P. Baptista 1 , T. Grant 2 , S. T. Renosto 1 , Z. Fisk 2 , A. J. S. Machado 1
1 Escola de Egenharia de Lorena, Universidade de São Paulo, P.O. Box 116, Lorena, SP,
Brazil.
2 Departments of Physics and Astronomy, University of California at Irvine, Irvine, CA
92697, USA
Layered transition metal dichalcogenides normally named TMDC’s of the type MX 2 (M
is transition metal, X = S, Se, Te) have been extensively studied for their rich electronic
properties due to low dimensionality. In these MX 2 materials each layer correspond to
the hexagonal transition metal intercalated by two similar chalcogen sheets and the
interaction between MX 2 layers is weak as van der Walls bonding between chalcogen
element (X). In general charge density wave (CDW) and superconductivity coexist in
these kinds of materials. Indeed, various compounds of this material class exhibits this
coexistence such as 2H-TaS 2 , 2H-NbS 2 , 2H-NbSe 2 etc. Within this scenario ZrTe 2 is an
interesting compound because also crystallize in a layered transition metal
dichalcogenides. In ZrTe 2 the prototype structure is CdI 2 which presents hexagonal
layers of transition metal intercalated by chalcogen elements. Some results reported in
literature about the electrical properties of ZrTe 2 show that this material presents
metallic behavior at a temperature interval from 4.0 K to 300 K. In this compound layer
of copper can be intercalate between Te-Te and may modify the electronic structure of
the (ZrTe 2 ) matrix compound. Thus, in this work we present results about intercalation
of Cu in the ZrTe 2 compound. The results suggest that the intercalation of Cu is able to
induce superconductivity in this compound. The superconducting critical temperature
close to 10.2 K is revealed through of magnetization and resistivity measurements. The
x-ray result reveals a new compound, originating from Cu intercalation and crystallizes
in the LiCrS2 prototype structure.
68

Vortex-Vortex interaction in two-component Bose-Einstein
condensates
A. R. P. Lima 1 , Davi S. Dantas 1 , Andrey Chaves 1 , G. A. Farias 1 , M. Milosevic 1,2 , F. M.
Peeters 1,2
1 Departamento de Física, Universidade Federal do Ceará, Caixa Postal 6030, Campus do Pici,
60455-900 Fortaleza, Ceará, Brazil.
2 Department of Physics, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp,
Belgium.
Since its proposal in 1924, the Bose-Einstein condensate is one of the main theories in
an attempt to explain phenomena such as superfluidity. On the other hand, a very close
link can be observed between the Gross-Pitaevskii theory of Bose-Einstein condensates
and the Ginzburg-Landau theory of superconductivity: in both cases, the main equation
governing the particles density is a non-linear Schrodinger-like equation.
It is well known that when a one-component condensate is set into rotation,
topological defects are created generating vortices which interact with each other
forming a triangular lattice. Similar phenomena occur in a type-II superconductor under
an external magnetic field. In a two component condensate, however, the interaction
between the both bands plays an important role in the cluster formation and defect
patterns can vary a lot according to the inter-band interaction strength. Recently, a
major effort was undertaken in an attempt to determine the interaction between vortices
in a condensate of two bands. [1] However, so far, only its asymptotic behaviour was
well established and the exotic vortex lattices encountered in recent works such as in [2]
were not well understood until now. Due to the similarities between both theories,
theoretical predictions made for vortices in multi-component Bose-Einstein condensates
can be easily linked to vortex lattices in multi-band superconductors.
Based on the recently published paper [3], where the interaction between
vortices in a two component superconductor were determined from the numerical
solution of a equation derived from Ginzburg-Landau equation, we suggest, in the
present work, a way of determining the interaction between vortices in a twocomponent
Bose-Einstein condensate. All the three kinds of interaction were
numerically calculated for different values of inter-band interaction. Once the
interaction between vortices is well defined, a Monte-Carlo study of the vortex lattice in
a rotating condensate was realized, in attempt (i) to validate our theory by obtaining
qualitatively similar patterns as those found in Ref. [2] and (ii) to predict new unusual
vortex lattices in these systems.
[1] A. Aftalion, P. Mason and J. Wei, Phys. Rev. A 85, 033614 (2012)
[2] P. Kuopanportti, J. A. M. Huhtamaki and M. Mottonen, Phys. Rev. A 85, 043613
(2012).
[3] A. Chaves, L. Komendova, M. V. Milosevic, J. S. Andrade Jr., G. A. Farias and F.
M. Peeters, Phys. Rev. B 83, 214523 (2011).
69

POSTER CONTRIBUTIONS
Dual view of the kinetic energy of superconductors
E. I. B. Rodrigues 1 , A. R. de C. Romaguera 1 , M. M. Doria 2 , A. A. Vargas-Paredes 2
1 Departamento de Física -Universidade Federal Rural de Pernambuco, Av. Dom Manoel de
Medeiros s/n, Dois IrmãosCEP: 52171-900 Recife, PE, Brazil.
2 Departamento de Física dos Sólidos -Universidade Federal do Rio de Janeiro, Av. Athos da
Silveira Ramos, 149-Centro de Tecnologia -Bloco A, Cidade Universitária -Ilha do Fundão
CEP: 21941-972, Rio de Janeiro, RJ,Brazil.
Since nuclear magnetic resonance studies have revealed [1] that damped spin
correlations exist across the entire range of doping for the cuprates, and with sufficient
intensity to mediate superconductivity, new questions have been raised for the
coexistence of superconductivity and magnetism [2,3,4]. Here we consider a quantum
macroscopic state approach, described by an order parameter (OP), as in the celebrated
Ginzburg-Landau theory, to find that magnetism and superconductivity coexist in a
single state.
The Lichnerowicz-Weitzenböck (LW) formula [5] is a mathematical relation
between a spinor operator, the covariant derivative and the curvature. Recently we have
claimed that this formula is a cornerstone of superconductivity from the
phenomenological point of view [6]. The concept of curvature in superconductors has
also been explored by other authors [7]. We derive the LW formula for the one (ψ) and
the two-component (Ψ) OP superconductors, in presence of mass anisotropy. Here the
curvature is just determined by the local magnetic field.
We consider kinetic energy of a one-component given by
and for case of two-component we assume the kinetic energy given by
the LW formula provided a twofold view of the kinetics energies,and consequently also
of the supercurrent. Remarkably it leads to a solution of Ampères law through first
order differential equations,which are central to e the present approach [8].
We have obtained first order equations able to determine the order parameter, the local
field and also an intrinsic magnetization. They were derived solely from the kinetic
energy and without relying in any particular assumption about the condensate energy.
[1] J. L. Miller, “Short-range spin waves may underlie high-temperature superconductivity,” Phys. Today, vol. 64,
no. 9, pp. 13–14, 2011. [2] E. Berg, E. Fradkin, S. A. Kivelson, and J. M. Tranquada, “Striped superconductors: how
spin,charge and superconducting orders intertwine in the cuprates,” New J. Phys, vol. 11, p. 115004, 2009. [3] M.
Vojta, “Lattice symmetry breaking in cuprate superconductors: Stripes, nematics, and superconductivity,” Adv.
Phys., vol. 58, no. 6, pp. 699–820, 2009. [4] R. Daou, J. Chang, D. Leboeuf, O. Cyr-choiniere, F. Laliberte, N.
Doiron-Leyraud, B. J. Ramshaw, R. Liang, d. A. Bonn, W. N. Hardy, and L. Taillefer, “Broken rotational symmetry
in the pseudogap phase of a high-t-c superconductor,” nature, vol. 463, no. 7280, pp. 519–522, 2010. [5] A.
Lichnerowicz, “Geometrie differentielle -spineurs harmoniques,” Comptes Rendus Hebdomadaires des séances de
l’Académie des sciences, vol. 257, no. 1, pp. 7–10, 1963. [6] M. M. Doria, A. A. Vargas-Paredes, and J. A. Helaylneto,
“The principle of local rotational invariance and the coexistence of magnetism, charge and superconductivity,”
Mod. Phys. Lett. B, vol. 26, no. 11, p. 1230005, 2012. [7] D. G. Barci and E. Fradkin, “Role of nematicfluctuations in
the thermal melting of pair-density-wave phases in two-dimensional superconductors,” Phys. Rev. B, vol. 83, p.
100509, 2011. [8] M. M. Doria, A. R. d. C. Romaguera, and F. M. Peeters, “The ground states of the two-component
order parameter superconductor,” Europhys. Lett., vol. 92, no. 1, 2010.
70

Ginzburg-Landau theory applied to the two bands mesoscopic
superconductor
Karciano J. S. Silva and Antonio R. de C. Romaguera
Departamento de Física, Universidade Federal Rural de Pernambuco, Recife, Brazil.
Despite of being studied for more than a century, the superconductivity remains afield
of current research and it has contributed signi_cantly to the development of the science.
Researchers have observed that the superconducting properties of mesoscopic
samples (superconductors that have dimensions on the order of the coherence and
penetration lengths) di_er from bulk samples. For better understanding of these different
mesoscopic superconductors, we studied the behavior of a two bands mesoscopic
superconductor which has the shape of a disc (with radius R and thickness t), placed in
an uniform magnetic _eld. We used the variational principle applied to the Ginzburg-
Landau theory (GL) to express the order parameters as an expansion of eigenfunctions
of a linear operator similar to the Schr• oendinger equation. The set of eigenfunctions
used in the variational principle is found using the software Comsol TM . The whole
procedure is performed in the Matlab TM environment. In relation to the order
parameters, we considered two different cases: First - one term for the variational
expansion of the order parameter for each band. In this way, we can describe the
Meissner and giant vortex states in each band. Second - two terms for the variational
expansion of the order parameter for _rst band and one term for the second band. When
the order parameter has two terms the variational procedure can describe the Meissner
and giant vortex states, as in the _rst case, and also the multi-vortex states. We also
considered two types of couplings between the bands: the Josephson and Cooper pairs
density couplings.
Variational principle allowed us to obtain an equation for the GL free energy, as
well as their stability conditions, as a function of the set of eigenfunctions. We also
obtained the free energy curves and phase diagram R vs H. Other important result was
to derive a fractional magnetic ux equation for the two bands superconductor.
This work counts with the financial support of the Brazilian financial agency FACEPE.
71

POSTER CONTRIBUTIONS
Structural, microstructural magnetic and electrical characterization of
ferromagnetic/superconducting hybrid systems
D. R. B. Valadão 1 , F. S. Portela 2 , L. T. Corredor 1,2 , E. Padrón-Hernández 1,2 , Petrucio Barrozo 3 ,
J. Albino Aguiar 1,2
1
PGMTR, Universidade Federal de Pernambuco, 50670-901, Recife-PE, Brazil
2 Departamento de Física, Universidade Federal de Pernambuco, 50670-901, Recife-PE, Brazil
3 Departamento de Física, Universidade Federal de Sergipe, 49032-150, São Cristovão-SE,
Brazil.
In this work we present studies of the preparation and structural, microstructural,
magnetic and transport characterization of ferromagnetic/superconducting hybrid
system. This hybrid systems are being widely studied because, in this configuration, on
can study how the superconducting parameters, such as, the second superconducting
critical field and, the vortex configuration and dynamics are affected by the magnetic
layer. The anodic aluminum oxide pores filled with different magnetic materials and
superconductor film deposited on the top of the pores is an example of this hybrid
system.
The anodic aluminum oxide pores have been produced by anodizing of
aluminum foil in two steps anodization [1]. Nickel, Cobalt and Iron nanowires were
electrodeposited within the pores by ac electrodeposition. The superconductor film was
deposited by sputtering. The Scanning Electron Microscopy (SEM) micrographs reveal
that the anodic aluminum oxide pores have an average diameter of the 40 nm and a
thickness about 8 μm. Energy Dispersive X-Ray (EDS) analysis confirmed the
deposition of magnetic nanowires and show that the length of the deposited nanowire is
approximately 2 μm. Magnetization measurements show that the samples present a
ferromagnetic behavior and that the hysteresis loop is wider when the external magnetic
field is applied parallel to the wires and narrower when the field is applied in the
perpendicular direction. Due to their extremely high aspect ratio and a strong
longitudinal magnetic anisotropy the magnetic nanowires tend to be magnetized along
their length, this provides a magnetic field perpendicular to the superconducting film
[2]. The magnetic field generated by the wires may strongly influence the
superconductor properties. Transport studies will allow determining how the
superconducting properties of the films will be affected by presence of the nanowires.
Keywords: Magnetic/superconductor hybrid systems, Nanowire, Anodic aluminum
oxide.
[1] Hideki Masuda and Kenji Fukuda. Science 268, 1466 (1995).
[2] Zuxin Ye, at all. Superconductor Science and Technology 24, 024019 (2011).
We thank Professors of UFPB Severino Jackson Guedes Lima and Tibério Andrade
Passos by SEM pictures. Work supported by CAPES, CNPq AND FACEPE (APQ-
0589/1.05-08)
72

Preparation and characterization of Fe 3 O 4 - Fe 2 O 3 / graphene oxide
composite.
B. A. G. Rodríguez 1,2 , Ricardo Batista 2 , Luis De Los Santos Valladares 2,3 , L. T. Corredor 2 , J.
Albino Aguiar 1, 2
1 Pós-Graduação em Ciência de Materiais, UFPE,Recife, Brazil.
2 Laboratório de Superconductividad e Materiais Avançados, Departamento de Física, UFPE,
Recife, Brazil.
3 Cavendish Laboratory, University of Cambridge, J. J Thomson Av., Cambridge CB3 0HE,
United Kingdom
At present the development of electronic nanodevices has allowed great advances in
technology. The graphene has been established as a key material with great advantages
for making nanodevices, due to its excellent properties such as, high strength (~1060
GPa), high thermal conductivity (~3000 Wm-1K-1), high electron mobility 15000 cm 2
V - 1 s -1 , high surface area 2600 m 2 /g, among other properties [1-2]. However, the
application of graphene in the electronic devices manufacturing can be limited, due to
difficulty in the direct obtaining of graphene. An alternative for this issue is the
production of graphene oxide (GO).
The GO has almost the same properties as conventional graphene and it is
relatively simple to manufacture, the surface of the GO has functional groups such as
epoxy groups, carboxyl groups, hydroxyl; these groups can decrease the electrical
properties of graphene. However, metallic nanoparticles can be anchored in the GO
surface to increase the conductivity properties of the graphene and giving new
properties [3-4].
In this work, we present the fabrication of GO by exfoliation of graphite powder
with the subsequent anchoring of metallic particles (Fe3O4/Fe2O3) on the graphene
oxide surface. The graphene oxide obtained was morphological and structurally
characterized by scanning electron microscopy (SEM), mapping energy-dispersive X-
ray spectroscopy, diffraction rays-x (XRD), infrared (IR), and Raman spectroscopies
and finally, magnetic measurements were carried out on a SQUID MPMS system.
Work financed by CNPq, CAPES and FACEPE (Grant 0589/1.05-08).
[1] Mingxin Ye, et al. J Phys Chem. c 2010,Vol.114, 1498
[2] Ganganahalli K. Ramesha and Srinivasan Sampath, J Phys Chem. C, 2009, Vol.
113, 7985
[3] Ryan Muszynski, Brian Seger and Prashant V. Kamat, Chem. C, 2008, Vol. 112,
5263
[4] Ian V. Lightcap, Thomas H. Kosel, and Prashant V. Kamat, Nano Lett. 2010, 10,
577
73

POSTER CONTRIBUTIONS
Crossover between BCS superconductor and BEC states in the
attractive Anderson lattice model
Daniel Reyes 1 , Mucio A. Continentino 2
1 Departamento de Física Teórica, Universidade do Estado do Rio de Janeiro, Rua São
Francisco Xavier 524, 20550-013 Rio de Janeiro, RJ, Brazil.
2 Centro Brasileiro de Pesquisas Físicas, Rua Dr. Xavier Sigaud, 150-Urca, 22290-
180 RJ, Brazil.
Using the method of Green functions equation of motion we considered the three
dimensional Anderson lattice model with attractive interaction between f-electrons. We
studied the appearance of superconductivity as a function of this attractive interaction
and a hybridization between localized f-electrons and conduction c-electrons. The zero
temperature phase diagram as a function of the hybridization and the strength of the
attractive interaction is obtained. In this phase diagram a quantum phase transition is
found which is characterized by a break up of the conventional BCS superconductor
state, as the hybridization increases after a certain critical value, Vc, and, at the same
time, the beginning of a metallic-like state with preformed pairs. At sufficiently large
attractive interactions and for V > Vc, a superfluid state of Bose condensed pairs
appears. We investigate for a possible coexistence between these pairs that form the
superfluid state, characterized by gapped dispersion relations, and the metallic-like state
characterized by gapless electronic excitations.
74

Effect of Dy dopping on the structural, microstructural and magnetic
properties of ruthenium pyrochlores Gd 2-x Dy x Ru 2 O 7
M. D. R. Marques 1 , A. M. Silva 2 , J. Albino Aguiar 1
1 Programa de Pós-Graduação em Ciência de Materiais, Universidade Federal de Pernambuco,
PE, Brazil
2 Departamento de Física, Universidade Federal de Pernambuco, PE, Brazil
Oxides with the pyrochlore-type structure, with the general formula A 2 B 2 O 7 , have
attracted great attention recently because of their unique cationic sublattice of cornersharing
tetrahedra, providing magnetic systems with geometrical frustration and
interesting physical properties at low temperatures. They exhibit a wide variety of
electrical and magnetic properties. The most remarkable magnetic characteristic is the
spin-glass transition with apparent absence of magnetic long-range order. In this work,
we present a systematic study of structural and magnetic properties the ruthenium
pyrochlores Gd 2 Ru 2 O 7 as well as the effect of doping Gd site in the structure Gd 2-
xDy x Ru 2 O 7 . Polycrystalline samples of ruthenium pyrochlore were prepared by solidstate
reaction method, where quantities of Gd 2 O 3 , RuO 2 and Dy 2 O 3 were weighed in the
correct metal ratios and dissolved in concentrated nitric acid. The excess nitric acid was
removed by gentle heating. The remaining powders were slowly heated to 400 °C for 3
h and heated at 850 °C for 24 h. After cooling to room temperature, the samples were
crushed into powders, reground, pressed into pellets, and then reheated at 1100 °C for
24 h. The samples were structurally by X-ray diffraction (XRD), microstructurally by
Scanning Electron Microscopy (SEM) and magnetically by recording magnetization as
a function of temperature and magnetic field. XRD patterns were analyzed by Rietveld
refinement, allowing the identification of single-phased compounds. SEM observation
revealed that the synthesized rare earth ruthenates have a relatively narrow size
distribution and uniform shape with a rough surface structure. The temperature
dependence of the magnetic susceptibility results show that the Gd 1.8 Dy 0.2 Ru 2 O 7 sample
present a paramagnetic behavior. Currently we are studying other Dy concentration. The
results will also be reported.
Work supported by CAPES, CNPq and FACEPE (APQ-0589/1.05-08).
75

POSTER CONTRIBUTIONS
Magnetic Studies of hematite hollow sub-micron spheres
S. Espinoza 1,2 , Á. Bustamante 2 , L. De Los Santos Valladares 3,4 , L. León 5 , J. Albino
Aguiar 4 .
1
TECSUP, Av. Cascanueces 2221, Sta. Anita. Lima 43, Peru.
2 Laboratorio de Cerámicos y Nanomateriales, Facultad de Ciencias Físicas, Universidad
Nacional Mayor de San Marcos, Ap. Postal 14‐0149, Lima, Peru.
3 Cavendish Laboratory, J.J. Thomson Av., University of Cambridge, Cambridge CB3 0HE,
United Kingdom.
4 Laboratório de Superconductividades e Materiais Avançados, Departamento de Física,
Universidad Federal de Pernambuco 50670‐901, Recife, Brazil.
5 Núcleo de Física Aplicada, Institute of Physics, Universidade de Brasília, Brasília, DF
70910‐900, Brazil.
The use of hollow iron oxide nanostructures is promising for anti-cancer drug
encapsulation and for its control and treatment. The iron oxide nano-structures may be
manipulated and / or controlled with the aid of an externally magnetic field applied,
guiding their position to specific areas where the cancer tumour is. In this work, the
magnetic characterization of hematite hollow spheres which are easily obtained by
starting a colloidal suspension of ferric nitrate (Fe(NO 3 ) 3 9H 2 O) in a citric acid solution,
following the sol-gel method and annealing at 600 °C are reported. The magnetic
properties were studied by the temperature dependence of the magnetic moment (M(T))
and the magnetic hysteresis loops at different temperatures (M(H)). Thermal hysteresis
is detected in the zero field cooling (ZFC) and field cooling (FC) branches of the M(T)
measurements (Morin transition). This effect confirms the formation of hematite. The
temperature transition from ferromagnetic to anti-ferromagnetic was around 250 K. A
Mössbauer spectroscopy study of the Morin transition is also included.
76

Simulation and Analytical results of vortex-antivortex motion in a
Corbino disk with a magnetic dipole on top
Belisa R. C. H. T. de Aquino 1 , Leonardo R. E. Cabral 1 , Clécio C. de Souza Silva 1 , J. Albino
Aguiar 1 , Milorad V. Milošević 2 , François M. Peeters 2
1 Departamento de Física, Universidade Federal de Pernambuco, Cidade Universitária, 50670-
901, Recife, Brazil
2 Departement Fysica, Universiteit Antwerpen, Groenenborgerlaan 171, B-2020 Antwerpen,
Belgium
Since the prediction of the vortex lattice by Abrikosov, vortices in superconductors have
been intensively studied. Recently, a great deal of attention has been given to the
dynamical properties of vortex-antivortex (v-av) molecules induced in superconducting
films with magnetic dipoles on top. In this work we study v-av dynamics in the Corbino
disc geometry with a magnetic dot on top. The dot is magnetized out of plane in order to
stabilize v-av configurations, with vortices closer to the center of the disc and
antivortices near the disc edge. Vortices and antivortices are induced to move in
opposite azimuthal directions by the radially applied electric current, which decays as
the inverse of the distance to the center of the disc. Different dynamical phases are
observed due to the interplay between the spatially inhomogeneous current distribution,
the screening currents induced by the dipole, and the attractive v-av interaction. Only at
very strong drive, v-av attraction is overwhelmed by the external current Lorentz force,
causing them to move in opposite directions. At current values below a threshold
current, antivortices remain bounded to vortices and the whole configuration rotates
rigidly. Above a threshold current, vortices and antivortices unbind and move in a
highly correlated way. The antivortices decouple from vortices and move at different
angular velocity until connect to the next vortex. This detaching and reconnection gives
rise to peaks in the angular velocities of both vortices and antivortices during time. The
time elapsed between two adjacent peaks is the time required for an antivortex to detach
from one vortex and reconnect to the next vortex. The dependence of the frequency of
occurrence of those peaks on the applied current goes as the square root of the
difference between the applied current squared and threshold current squared. Also the
electric field and electric potential are investigated (I-V curves). In order to better
understand the simulation results, we modeled the v-av system and compared the
analytical and simulation results. The analytical results describes the two vortex and
antivortex shells motion and shows a good agreement with the v-av dynamics observed
during simulations.
77

POSTER CONTRIBUTIONS
Síntese e caracterização estrutural de partículas de ferro
Ricardo Batista do Carmo 1 , B. A. G. Rodríguez 1,2 , J. Albino Aguiar 1
1
Laboratório de Superconductividad e Materiais Avançados, Departamento de Física, UFPE,
Recife, Brazil.
2
Pós-Graduação em Ciência de Materiais, UFPE,Recife, Brazil.
O estudo das partículas magnéticas usadas por várias décadas para aplicações de
reparação de água, utilidade em biomedicina, sensores, etc, os processos de sínteses são
variados, os reagentes mais comuns para a fabricação de partículas são cloreto férrico II
e cloreto férrico III ou sulfato de ferro, apesar de utilizar diferentes métodos e reagentes,
por vezes, resulta em uma mistura de partículas, tais como Fe 3 O 4 , Fe 2 O 3 , e o contato
com a atmosfera do oxidante extingue estas partículas, formando outros compostos
alguns derivados de óxido de ferro.
Neste documento apresenta-se a síntese de diferentes partículas de Fe3O4, em
que cada processo terá uma pequena mudança quando a temperatura aumenta durante a
síntese ou, simplesmente, utilizando reagentes diferentes, mostram a caracterização por
difração de raios X, o cálculo do tamanho do cristalito pela equação Deby Scherrer, a
identificação dos planos.
78

Characterization and Study of superconducting properties of
multilayer thin films
F. S. Portela 1 , L. T. Corredor 1 , Petrucio Barrozo 2 , J. Albino Aguiar 1
1 Departamento de Física, Universidade Federal de Pernambuco, 50670-901,Recife-PE, Brazil
2 Departamento de Física, Universidade Federal de Sergipe, 49032-150, São Cristovão-SE,
Brazil.
The study of superconducting multilayer has attracted much interest in science and
technology because of their interesting physical properties. The main study in this area
is the Josephson coupling that occurs between layers of superconducting materials with
a layer of semiconductor material between them. In other systems, it can also be studied
proximity effect between superconductive layers with a normal material barrier.
However, little is discussed about the study of multilayer when both materials are
superconductors. In this paper we focus our attention on multilayer composed of
elementary superconducting materials (Nb, Pb and Sn), each sample made up of type 1
and type 2 superconductors with 50 nm thickness, except for Nb(50 nm) / Pb(500 nm).
The designed systems were Nb/Pb, Nb/Sn, Pb/Sn, Cr/Nb/Cr and Sn/Pb/Sn. Multilayer
were prepared on glass and MgO substrates at room temperature, with deposition via
magnetron sputtering using DC and RF sources and pressure of 3.7 mTorr Ar. The
sputtering chamber was evacuated to 10-7 Torr before deposition by using solid Nb, Pn
and Sn targets with high purity. Layer thicknesses were controlled during growth with
quartz-crystal monitors. The multilayer was characterized by x-ray diffraction and
Scanning Electron Microscopy (SEM). Magnetization measurements M(T) and M(H)
were studied with a SQUID magnetometer. The superconducting transitions were
investigated as a function of temperature and magnetic field in a four probe
configuration by using a Physical Property Measurement System (Quantum Design,
PPMS).
Keywords: Superconducting properties, thin films.
79

POSTER CONTRIBUTIONS
Polarized Raman spectroscopy in LaFeAsO system
U. F. Kaneko 1 , P. F. Gomes 1 , A. F. Garca-Flores 1 , D. Vaknin 2,3 , E. Granado 1
1 Instituto de Física Gleb Wataghin, Universidade Estadual de Campinas, Campinas, São Paulo
13083-859, Brazil.
2 Ames Laboratory, US-DOE, Ames, Iowa 50011 USA.
3 Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, USA.
We have probed single crystals of LaFeAsO using polarized Raman spectroscopy which
enabled us to observe the well known Tetragonal(T)-to-Orthorhombic(O) structural
transition at TS ≈ 155 K. Besides, it is possible correlate the signal increase at low
frequency with the presence of antiferromagntic (AFM) order at TN _ 140 K.
Additionally, it is shown that both phases T and O may dynamically coexist in a short
temperature range below TS.
This work was supported by FAPESP and CNPq, Brazil.
80

Superconductivity and magnetism in the K x MoO 2-
L. M. S. Alves, C. A. M. dos Santos, S. S. Benaion, C. M. Romanelli, A. J. S. Machado, B. S. de
Lima
Escola de Engenharia de Lorena, Universidade de São Paulo, Lorena - SP, 12602-810, Brazil
This work reports the physical properties of the K x MoO 2- polycrystalline samples
[1,2]. Results of x-ray diffraction and simulations performed by the GSAS program
show that the samples obtained are of good quality. Photoemission spectroscopy shows
the existence of high fraction of Mo 3+ /Mo 4+ in several samples of the K x MoO 2- [2].
Results of magnetization and electrical resistivity confirmed the existence of
superconductivity in the K-Mo-O system [1,2]. It was observed that critical temperature
(T C ) depends on the initial K composition in the samples. The highest T C reported for
this system is T C ~9.5 K. Magnetization measurements also showed the coexistence of
magnetism and superconductivity in the K x MoO 2- compound [2]. Preliminary results
suggest that the Mo 3+ ions are responsible for the magnetism of the compound [3].
Magnetic ordering temperature (T M ) and superconducting critical temperature (T C ) ratio
ranges from 7 to 18 in the compound. These are the highest ratio reported so far for a
magnetic superconductor. Finally, measurements of specific heat and electrical
resistivity showed the existence of a phase transition at high temperatures (between 250
and 270 K). This transition is discussed based upon the motion of Mo atoms in the Mo-
Mo one-dimensional bonds from rutile to monoclinic structure [4].
Authors thank FAPESP (2009/54001-2, and 2010/06637-2) and CNPq
(508308/2010-0, 309084/2010-5, and 490182/2009-7). J. J. Neumeier, M. D. R.
Marques, J. Albino Aguiar, R. J. O. Mossanek, M. Abbate, and E. Guedes are also
acknowledged for some measurements and discussions.
[1] Alves, L. M. S., Damasceno, V. I., Dos Santos, C. A. M., Bortolozo, A. D., Suzuki,
P. A., Izário Filho, H. J., Machado, A. J. S., and Fisk, Z. Phys. Rev. B, v. 81, p. 174532,
2010.
[2] Alves, L. M. S., dos Santos, C. A. M., Benaion, S. S., Machado, A. J. S., de Lima,
B. S., Neumeier, J. J., Marques, M. D. R., Albino Aguiar, J., Mossanek, R. J. O., and
Abbate, M. J. Appl. Phys., v. 112, p. 073923, 2012.
[3] Hong, N. H., Sakai, J., Poirot, N., and Briz, V. Phys. Rev. B, v. 73, p. 132404, 2006.
[4] Romanov, D. P., and Skrobot, V. N. Glass Phys. and Chem.,v. 35, p.518, 2009.
81

POSTER CONTRIBUTIONS
Hematite sub-micron hollow spheres: Thermal formation and
magnetic properties
Luis De Los Santos Valladares 1,2 , L. León-Félix. 3,4 , A. Bustamante 3 , M. Espinoza Suárez 3 , J.
Albino Aguiar 2
1
Cavendish Laboratory, Department of Physics, University of Cambridge, J.J. Thomson
Avenue, Cambridge CB3 0HE, United Kingdom.
2
Laboratório de Supercondutividade e Materiais Avançados, Departamento de Física,
Universidade Federal de Pernambuco 50760-901, Recife, Brazil.
3
Laboratorio de Cerámicos y Nanomateriales, Facultad de Ciencias Físicas, Universidad
Nacional Mayor de San Marcos, Ap. Postal 14-0149, Lima, Perú.
4 Núcleo de Física Aplicada, Instituto de Física, Universidade de Brasília, Brasília, DF 70910-
900, Brazil.
In this work, we report the thermal formation and magnetic properties of α-Fe 2 O 3 submicron
hollow spheres. X-ray diffraction analysis confirms the formation of the α-Fe 2 O 3
phase after sintering at 773, 823 and 823 K. Scanning electron microscopy images
reveal the formation of hollow spheres after the sintering at 823 K. The evolution of the
Morin transition is studied by magnetic measurements. Mössbauer spectroscopy
measurements at room temperature and 77 K show that the hyperfine parameters depend
on the temperature of annealing and indicate the occurrence of the Morin transition in
the hollow spheres.
82

Synthesis and characterization of nanoparticles of cobalt ferrite for
immobilization
P.L. Andrade 1,2 *, V.A.J. Silva1 2 , J.C. Maciel 2 , N.O.Moreno 3 , S.M.B. Pereira 4 , M.P.C. Silva 2 and
J.Albino Aguiar 1,5
1 Programa de Pós-Graduação em Ciências de Materiais, CCEN, Universidade Federal de
Pernambuco, Recife, Brazil.
2 Laboratório de Imunopatologia Keizo Asami and Departamento de Bioquímica, UFPE,
Recife, Brazil.
3 Departamento de Fisíca, Universidade Federal de Sergipe, São Cristovão, Brazil.
4 Departamento de Biologia, Universidade Federal Rural de Pernambuco, Recife, Brazil.
5 Departamento de Física, Universidade Federal de Pernambuco, Recife, Brazil.
Enzymes immobilization is considered to be an important tool to enhance thermal and
operational stability, easy separation from the reaction mixture during down streaming
and reusability for industrial applications [1]. An important requirement for protein
immobilization is that the matrix should provide a biocompatible and inert environment,
i.e. it should not interfere with the native structure of the protein, which thereby could
compromise its biological activity [2]. The purpose of this work was to study structural,
microstructural and magnetic characteristics of fucan coated magnetite particles and it
application as a solid support for enzymes immobilization. Magnetic particles were
prepared in the presence of polysaccharide fucan. Aqueous suspension of magnetic
particles were prepared by coprecipitation of Fe(III) and Co(II) in the presence of
NaOH and polymer. The samples were characterized by X-ray diffraction, electron
scanning microscopy (SEM), Mössbauer spectrocopy and magnetization. The coating
produced changes in the size and morphology of magnetite particles. These magnetic
nanoparticles were used as matrix for enzyme immobilization. The immobilized trypsin
in cobalt ferrite with oleic acid and fucan presented a specific activity of 52% after 10
reuses.
Keywords: Nanoparticles, cobalt ferrite, immobilization, fucan.
Work financed by CAPES, CNPq AND FACEPE (APQ-0589/1.05-08).
[1] Mateo C, Palomo JM, Fernandez-Lorente G, Guisan JM, Fernandez-Lafuente R.
Improvement of enzyme activity, stability and selectivity via immobilization
techniques. Enzym Microb Technol 2007;40:1451–63.
[2] Ansari, S. A., Husain, Q. Potential applications of enzymes immobilized
on/in nano materials: A review. Biotechnology Advances, 2012, 30, 512-523.
83

POSTER CONTRIBUTIONS
Preparation and characterization of fucan-coated magnetite
nanoparticles for application on antitumor activity
V. A. J. Silva1 2 *, P. L. Andrade 1,2 , A.G. Bustamante Dominguez 4 , M. M. Quien 4 , I. A. Souza 5 ,
K. P. S. Cavalcanti 6 , M. P. C. Silva 2 , J. Albino Aguiar 1,3
1 Programa de Pós-Graduação em Ciências de Materiais, CCEN, UFPE, Recife, Brazil.
2 Laboratório de Imunopatologia Keizo Asami (LIKA), Departamento de Bioquímica, UFPE,
Recife, Brazil.
3 Laboratório de Supercondutividade e Materiais Avançados, Departamento de Física, UFPE,
Recife, Brazil.
4 Laboratrio de cerámicos y nanomateriales, Universidad Nacional Mayor de San Marco, Lima,
Peru.
5 Departamento de Antibióticos, UFPE, Recife, Brazil.
6 Hospital das Clínicas, UFPE, Recife, Brazil.
Magnetic nanoparticles (MNPs) are a class of nanoparticles that can be manipulated
under the influence of an external magnetic field [1]. In recent years, superparamagnetic
nanoparticles were widely used in the field of biology and medicine, such as protein and
enzyme immobilization, bioseparation, immunoassay, hyperthermia, drug delivery,
tissue engineering, magnetic resonance imaging (MRI) [2]. Fucans are sulfated
polysaccharides, constituents of brown algae and possess many biological activities
such as anticoagulant, antiviral, antitumoral, anti-inflammatory [3]. The objective of this
work was to synthesize fucan-coated magnetite nanoparticles by co-precipitation
method, to characterize and to utilize them for antitumoral activity. The characterization
was performed by scanning electron microscopy (SEM), transmission electron
microscopy (TEM), X-rays diffraction, magnetization and Mossbauer spectroscopy. The
surface morphology and the nanoparticle size of magnetite and magnetite-fucan were
observed by SEM and TEM. It was observed that the samples present a heterogeneous
morphology and average size between 10 and 20 nm. The X-ray showed that the surface
of magnetite-fucan nanoparticles the characteristic peaks did not disappear but these
exhibited lower intensity and amorphous characteristics. The magnetization curve
indicates that magnetite-fucan nanoparticles exhibit a typical superparamagnetic
behavior. It shows no hysteresis loops at room temperature and exhibits zero of
remanence and coercivity. This superparamagnetic behavior was confirmed by
Mossbauer spectra. These magnetic nanoparticles were applied for antitumoral activity
in mice with Sarcoma 180 and the preliminary results indicate a reduction of tumor size.
Keywords: magnetite nanoparticles, sulfated fucan, antitumor activity.
Work supported by CAPES, CNPq and FACEPE (APQ0589-1.05/08).
*Corresponding author: valdeene@hotmail.com
[1] V. I. Shubayev, T. R. Pisanic, S. Jin. Adv. Drug Delivery Rev. 61 (2009), 467–477.
[2] L. Zhang, X. Zhu, H. Sun, G. Chi, J. Xu, Y. Sun. Current Applied Physics 10
(2010), 828–833.
[3] P. Karmakar, T. Ghosh, S. Sinha, S. Saha, P. Mandal, P. K. Ghosal, B. Ray. Carb.
Polym. 78 (2009), 416–421.
84

Localized superconductivity near magnetic disks embedded in thin
films
Tiago T. Saraiva and Clécio C. de Souza Silva
1 Departamento de Física, Universidade Federal de Pernambuco
The confinement of quantum systems provides a lot of interesting phenomena such as the
quantization of the energy of particles confined in a potential well. Usually we say that we are in
the mesoscopic scale when the system is much larger than atoms and molecules but small
enough to have quantum properties. Recent fabrication and characterization techniques allow
for studying the behavior of small superconducting systems with size of order of the coherence
and penetration lengths and many new aspects concerning the sample geometry have been
found. Our interest is to describe hybrid superconductor/ferromagnet samples [1] which have
multiply connected surfaces [2]. In this work we studied analytically the stationary states of the
localized superconductivity phase in thin films with a magnetic inclusion of size of the order of
the coherence length, submitted to a magnetic field perpendicular to the film [3]. Using the
linearized Ginzburg-Landau equations we show that the nucleation of the superconductivity
happens for field values above the bulk critical field H c2 , in a region nearby the magnetic dot
despite the fact that the Cooper pairs density at the magnet-superconductor interface is zero.
Such systems may be used to create devices that need to remain in the superconducting phase at
high magnetic fields.
[1] M. V. Milosevic, S. V. Yampolskii, and F. M. Peeters. Phys. Rev. B, 66:024515,
2002.
[2] A. Bezryadin and B. Pannetier. Journal of Low Temperature Physics, 98:251_268,
1995.
[3] A. Yu. Aladyshkin, D. A. Ryzhov, A. V. Samokhvalov, D. A. Savinov, A. S.
Mel'nikov, and V. V. Moshchalkov. Phys. Rev. B, 75:184519, 2007
85

POSTER CONTRIBUTIONS
The electrical, magnetic and structural properties of the system
La 2 CoMnO 6 prepared by the method of combustion after different
atmospheres and treatment setup
Pedro Linhares Filho
Universidade Federal de Pernambuco, Av. Prof. Moraes Rego 1235, Cidade Universitária,
CEP: 50670-901, Recife PE, Brazil
La 2 CoMnO 6 samples prepared by combustion method have been treated within the
temperature range of 800 ºC for 16 h and 1300 ºC for 2 h at ambient, oxidizing (O 2 ) and
reducing (N 2 ) atmospheres, and cooled at rates ranging from 20 K.min-1 and 180
K.min-1. The properties are structural, electrical and magnetically characterized, where
monoclinic ordered perovskite proved to be partially ordered with transition metals
within Co 2+ and Mn 4+ configurations, rhombohedral disordered perovskite within Co 3+
and Mn 3+ configuration and orthorhombic accommodating different valences,
depending the heat treatment setup. Magnetization measurements as a function of
temperature and magnetic field revealed a paramagnetic state on the material at
temperature above 225 K, which ordering ferromagnetic or ferrimagnetically. At low
temperature the material behaves like a hard ferromagnet, while at high temperature
behaves as a soft ferromagnet. Electrical transport measurements showed that the
system is typically semiconductor at temperatures less than 150 K with 60 kOhm.m
resistivity’s, controlled by distinct mechanisms of conductivity versus temperature. Low
temperature shows mechanisms like small polarons, while at high temperature electrons
hopping mechanisms controlling the conductivity in the system. Between these two
mechanisms are active magnons influenced by spontaneous magnetization created by
the interactions between transition metal ions in the temperature range in which the
conductivity drops abruptly.
86

Application of a phenomenological model for the surface impedance in
high temperature superconducting films
A.S. Mosquera Polo 1,3 , D. A. Landínez Téllez 2 , L.T. Corredor 1 , J. Albino Aguiar 1
1 . Departamento de Física, Universidade Federal de Pernambuco, Av. Prof. Luis Freire s/n,
50670-901, Cidade Universitária, Recife-PE, Brazil
2 . Grupo de Física de Nuevos Materiales, Departamento de Física, Universidad Nacional de
Colombia, Bogotá DC
3 . Grupo de Nuevos Materiales, Departamento de Física, Universidad del Magdalena, AA
10004, Santa Marta, Colombia
We report the application of a phenomenological model for the microwave surface
impedance in high temperature superconducting films. This model is based on the
modified two-fluid model, in which the real and imaginary parts of the surface
impedance use the modelling parameter γ. This is responsible for the superconducting
and normal charge carrier density and is used for the description of the temperature
dependence of the London penetration depth λL(T) including λL(0). The relaxation time
model also uses the γ parameter in combination with the residual resistance parameter α.
The parameter δ 1

POSTER CONTRIBUTIONS
Study of the magnetic properties, the crystal, electronic and band
structures of the Sr 2 DyRuO 6 Complex Perovskite
C. A. Triana*, D. A. Landínez Téllez and J. Roa-Rojas
Grupo de Física de Nuevos Materiales (GFNM), Departamento de Física, Universidad
Nacional de Colombia,Bogotá D.C. Carrera 45 No 26-85, A.A. 5997, Colombia.
*Corresponding author. E-mail: ctrianae@unal.edu.co
A comprehensive investigation of the Sr2DyRuO6 complex perovskite was undertaken.
Crystal structure characterization performed by X-ray diffraction measurements and
Rietveld analysis allowed establishing that the material crystallizes in a distorted
monoclinic perovskite-like structure belonging to the P21/n (#14) space group, with an
alternating distribution of Ru5+ (2d: 0.5, 0, 0) and Dy3+ (2c: 0, 0.5, 0), making up RuO6
and DyO6 octahedra alternately arranged in two interleaving fcc sublattices. Because of
the mismatch in the ionic radii, the DyO6 and RuO6 octahedra are forced to tilt around
the cubic directions so as to optimize the Sr-O inter-atomic bond lengths, tending to
rotate the structure in order to fix the Ru5+ and Dy3+ on the M′ and M′′ sites of the
complex perovskite. Morphological characterization carried out by scanning electron
microscopy (SEM) indicated a particle size D=37.17 nm and an activation energy
Q=109.8 kJ/mol. Semi-quantitative compositional study, performed through energydispersive
X-ray (EDX) experiments, corroborated that the pure phase of the
Sr2DyRuO6 was correctly obtained. Magnetic properties determined from the fit of the
Curie-Weiss law to the curves of magnetic susceptibility as a function of temperature
showed that Sr2DyRuO6 exhibits an antiferromagnetic-like behavior at low temperatures
as a consequence of a magnetic transition at T=38 K. Data collected with respect to the
field dependence of the magnetization showed the existence of a weak ferromagnetic
moment relationship with antiferromagnetic-like behavior. Density functional theory
(DFT) allowed establishing the optimum electronic structure for Sr2DyRuO6, and the
study of the density of states (DOS) showed that Ru5+ and Dy3+ are responsible for the
magnetic character of the compound, with the prediction that at T=0 K it behaves as a
half-metallic material. The spin magnetic moment of the cell is close to 16 μB, and the
integer number of Bohr magneton is a signature of half-metallic character. Evolution of
crystal structure at high temperature in the range 298 K≤T≤1273 K revealed that
Sr2DyRuO6 does not undergo structural phase transitions, since the Bragg reflections
[hkl] over the whole temperature range do not undergo changes, and the structure is
preserved.
88

Magnetotransport and magnetization measurements in melt-textured
YBaCuO superconductors probed by pulsed magnetic fields
Fábio Teixeira Dias 1 , Valdemar das Neves Vieira 1 , Douglas Langie da Silva 1 , Sabrina
Esperança Nunes 1 , Frederik Wolff-Fabris 2 , Erik Kampert 2 , Jacob Schaf 3 , Joan Josep Roa
Rovira 4
1 Universidade Federal de Pelotas, 96010-900, Pelotas, BRAZIL
2 Dresden High Magnetic Field Laboratory, HZ Dresden-Rossendorf, 01314, Dresden,
GERMANY
3 Universidade Federal do Rio Grande do Sul, 91501-970, Porto Alegre, BRAZIL
4 Université de Poitiers, 86962, Poitiers, FRANCE
Among several techniques to grow high-temperature superconductors, melt-textured
techniques have emerged as an alternative way to produce materials with physical
properties needed for some technological applications. In this work we have studied the
correlation between the magnetic irreversibility line and the zero-resistance state in
melt-textured YBaCuO samples (Y123) with inclusions of Y211 phase particles by
performing magnetization and magnetotransport measurements in DC and pulsed
magnetic fields up to 60 T and temperatures down to 1.5 K. Our results show for inplane
magnetic fields an irreversibility field higher than 40 T at 77 K which evidences a
strong pinning effect due to the interface of the Y211 particles embedded in the Y123
phase. We have observed effects of the intrinsic pinning due to the anisotropic
superconductivity of the Y123 phase. Access to pulsed high magnetic fields reveals a
suppression of the low-temperature magnetic irreversibility field relative to BC2. These
results show experimental evidences for field induced microscopic quantum fluctuations
as observed in different high-Tc superconductors. Our findings in melt-textured YBCO
samples exclude the possibility that the zero-resistance state and the magnetic
irreversibility merge in this field range, showing evidences of weak granularity.
89

POSTER CONTRIBUTIONS
Possibility of the superconducting behavior in a new compound of
Mg 2 SnB x C x composition.
H. L. Santana, S. Renosto 1 and A. J. S. Machado.
Escola de Engenharia de Lorena – EEL – USP.
In the Mg-Sn system there is just one intermetallic compound of Mg 2 Sn composition.
This intermetallic compound crystallizes in a cubic structure with CaF 2 prototype. In
this structure there are many interstitial sites available. This intermetallic material has
been synthesized and studied as semiconductor material of potential interest in
microelectronic application. However, there is no found in literature some study that
reported the electronic behavior as a function of the interstitial doping atoms. Thus, in
this work we show that Mg 2 Sn compound when doped with boron and carbon
interstitial atoms, an interesting new superconducting behavior emerge even in low
content of interstitial doped. Our results suggest that this material doped with boron and
carbon in the Mg 2 SnB 0.5 C 0.5 stoichiometry can reach the suppressing superconducting
critical temperature close to 32.0 K. These results are sustained by resistivity and
magnetization measurements.
90

Synthesis and Characterization of KMo 4 O 6
M. Andrade, M. L. Maffei, L. M. S. Alves, C. A. M dos Santos, B. Ferreira and A. F. Sartori.
Escola de Engenharia de Lorena – USP, P. O. Box 116, Lorena, SP 12602-810, Brazil
ma@ppgem.eel.usp.br
The KMo 4 O 6 compound is an important molybdate that shows interesting physical
properties such as high anisotropy, structure with infinites chains with Mo 6 octahedra,
metal–insulator transition (MIT) near 120 K, and quasi-one-dimensional electrical
behavior [1]. This compound crystallizes into two phases. One has tetragonal structure
with space group P4/mbm, lattice parameters a = 9.612 Å and, c = 2.950 Å. The
synthesis of KMo 4 O 6 is commonly carried out by electrolysis of molten salts [2, 3]. One
the biggest issue in studying high anisotropic conductors and MIT is due to these
behaviors appear closed related to the superconductivity [4].
The crystals grew in the form of black square prisms with dimensions of 1.0 x
0.2 x 0.2 mm³. They were obtained from a mixture of K 2 MoO 4 and MoO 3 in the molar
ratio of 6:1, dried at 160 ° C and 450 ° C. The synthesis occurred with a current of 20 –
25 mA at 930 °C for 52 h. X- ray diffractometry confirmed that the crystals obtained
were due to the KMo 4 O 6 phase with the same characteristics reported previously [2,3].
Electrical resistances measurements were done by standard four-probe method using a
PPMS from 2 to 300 K. The results show metallic behavior with a MIT near 120 K.
Magnetic measurements were done parallel and perpendicular to the field in the range 2
– 300 K using a VSM coupled in a PPMS. The MxT curves agree with the magnetic
anisotropy reported previously. MxH curves display non-linear behavior at high
temperatures which suggest that the KMo 4 O 6 compound does not show a Pauli
paramagnetism as reported previously. The results also suggest magnetic ordering
which happens near the metal–insulator transition temperature.
Acknowledgement: FAPESP (2010/06637-2 and 2009/54001-2), CNPq (490182/2009-
7 and 309084/2010-5) and CAPES.
[1] K. V. Ramanujachary, M. Greenblatt, E. B. Jones and, W. H. M. C. Carroll, J. Solid
State Chem. 102, 69 (1993).
[2] W.H. McCarroll, K. V. Ramanujachary, M. Greenblatt and, Richard E. Marsh, J.
Solid State Chem. 117, 217 (1995).
[3] R. Hoffman, R. Hoppe, K. Bauer, and K. J. Range, J. Less Common Met.161, 279
(1990).
[4] C. A. M. dos Santos, B. D. White, Yi-Kuo Yu, J. J. Neumeier, and J. A. Souza,
Physical Review Letters 98, 266405 (2007).
91

Registered Participants
Registered Participants
Andrey Chaves (andrey@fisica.ufc.br)
Angel Guillermo Bustamante Domínguez (angelbd1@gmail.com)
Antonio Romaguera (antonio.romaguera@df.ufrpe.br )
Ariday Samit Mosquera Polo (ariday.mosquera@gmail.com )
Arthur Carvalho Scaramussa (arthur.scar@gmail.com)
Belisa Rebeca Cavalcanti Holanda Tavares de Aquino (rebecaholanda@gmail.com )
Blanca Azucena Gómez Rodríguez (blanca.azucena@ufpe.br )
Brian Maple (mbmaple@ucsd.edu )
Carles Navau (carles.navau@uab.cat )
Carlos Augusto Cardoso Passos (carlosaugustocp@gmail.com)
Clecio C. de Souza Silva (clecio@df.ufpe.br )
Custodio Ramalho M. (malico@alunos.eel.usp.br)
Daniel Reyes Lopez (daniel@cbpf.br )
Daniela Rodrigues Borba Valadão (danielavaladao.ufpe@gmail.com)
David Arsenio Landinez Tellez (dalandinezt@unal.edu.co)
Davi Soares Dantas (davisoaresdantas@gmail.com)
Edinardo Ivison Batista Rodrigues (edinardo_ivison@hotmail.com)
Edson Sardella (edsonsdl@fc.unesp.br)
Eduardo Cantera Marino (marino@if.ufrj.br )
Ernesto Govea Alcaide (egoveaa@udg.co.cu)
Fábio Teixeira Dias (fabio.dias@ufpel.edu.br)
Feo V. Kusmartsev (F.Kusmartsev@lboro.ac.uk)
Flávia Santos Portela (flaviaportela@df.ufpe.br)
François Peeters (francois.peeters@ua.ac.be)
Giovani Lopes Vasconcelos (giovani@df.ufpe.br)
Guilherme Gonçalves Sotelo (gsotelo@id.uff.br)
Helton Luis Santana (helton.skiter@gmail.com)
Ioan Adrian Crisan (i.a.crisan@bham.ac.uk)
Isaías Gonzaga de Oliveira (isaias@ufrrj.br)
Jackeline da Costa Maciel (jackeline_maciel@hotmail.com)
Jacqueline da Silva Sousa (sousa-js@hotmail.com)
Janaina Viana Barros (janavbarros@yahoo.com.br)
João Frederico Haas Leandro Monteiro (JFHLMONTEIRO@HOTMAIL.COM)
John Neumeier (neumeier@physics.montanta.edu)
Joshua L. Cohn (cohn@physics.miami.edu)
Joris Van de Vondel (joris.vandevondel@fys.kuleuven.Be)
Juscelino Batista Leao (juscelino.leao@nist.gov)
Karciano José Santos Silva (karciano@gmail.com)
Laura Teresa Corredor Bohórquez (ltcorredorb@df.ufpe)
92

Leandro Marco Salgado Alves (leandro@ppgem.eel.usp.br)
Leonardo R.E. Cabral (lrecabral@df.ufpe.br)
Lucas Eduardo Correa (lucas_edu_correa@alunos.eel.usp.br)
Luis De Los Santos Valladares (ld301@cam.ac.uk )
Margareth Andrade (ma@ppgem.eelusp.br)
Maria Danielle Rodrigues Marques (danielle@df.ufpe.br)
Mauro Ernesto Da Silva Júnior (ufrpefisica@yahoo.com.br)
Mauro Melchiades Doria (mauromdoria@yahoo.com.br)
Michael Cabrera-Baez (mcabrerapk@gmail.com)
Milorad Milosevic (milorad.milosevic@ua.ac.be)
Mohammed Elmassalami (massalam@if.ufrj.br)
Naiara Pasqualotti Baptista (naiara.baptista@yahoo.com.br)
Natacha A. Nogueira (natacha4404@yahoo.com.br)
Orlando Cigarroa Velázquez (orlandocv@ppgem.eel.usp.br)
Pedro Linhares Filho (linharesf@df.ufpe.br)
Petrucio Barrozo da Silva (petruciobarrozo@gmail.com)
Priscyla Lima de Andrade (priscylandrade@df.ufpe.br)
Rafael de Vasconcellos Clarim (rafaelclarim@gmail.com)
Renato de Figueiredo Jardim (rjardim@if.usp.br)
Ricardo Batista do Carmo (ricardobatista19@hotmail.com)
Romualdo Santos Silva Junior (romu.fisica@gmail.com)
Rustem Khasanov (Rustem.khasanov@psi.ch)
Sergey L. Bud’ko (budko@ameslab.gov)
Sergio Machado Rezende (rezende@df.ufpe.br)
Sergio Tuan Renosto (str@ppgem.eel.usp.br)
Sérgio Wlademir da Silva Apolinário (sergiowsa@df.ufpe.br)
Silvia Marisel Espinoza Suárez (sespinoza@tecsup.edu.pe)
Simone Aparecida da Silva (silmone307@gmail.com)
Thiago Luis Schneider (thiago.luis.schneider@gmail.com)
Tiago T. Saraiva (tiagosaraiva@df.ufpe.br)
Ulisses Ferreira Kaneko (ulisseskaneko@gmail.com)
Valdeene Albuquerque Jansen da Silva (valdeene@hotmail.com)
Wilmer Yecid Córdoba Camacho (wilmeryecid18@hotmail.com)
Yuri Aparecido Opata (yuriopata@gmail.com)
Yutao Xing (xing@if.uff.br)
Zachary Fisk (zfisk@uci.edu)
93