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Tuesday Scattering theory of nonlinear thermoelectric transport David Sánchez Institute for Cross-Disciplinary Physics and Complex Systems IFISC (UIB-CSIC), E-07122 Palma de Mallorca, Spain We discuss nonlinear transport properties of quantum conductors in response to both electrical and thermal driving forces. Within scattering approach, we determine the nonequilibrium screening potential of a generic mesoscopic system and find that its response is dictated by particle and entropic injectivities which describe the charge and entropy transfer during transport. We illustrate our model analyzing the voltage and thermal rectification of a resonant tunneling barrier. Importantly, we investigate interaction induced contributions to the thermopower in the presence of large temperature differences [1]. [1] D. Sánchez and R. López, arxiv:1209.1264 (preprint, 2012). __________________________________________________________________________ Magnon-driven quantum-dot heat engine Björn Sothmann, Markus Büttiker Département de Physique Théorique, Université de Genève, CH-1211 Genève 4, Switzerland The concept of harvesting energy from the environment to power small devices has become increasingly popular. Recently, there was a particular interest in quantum dot systems that generate electrical currents from thermal fluctuations [1,2]. The main focus of the emergent field of spin caloritronics is the idea to drive and control spin currents by heat. Here, we discuss a setup consisting of a single-level quantum dot coupled to two ferromagnetic metals and a ferromagnetic insulator held at different temperatures which combines the ideas of energy harvesting and spin caloritronics. We demonstrate that this nanoengine can act as an optimal heat to spin-polarized charge current converter in an antiparallel geometry, while it acts as a heat to pure spin current converter in the parallel case. We discuss the maximal output power of the device and its efficiency [3]. [1] R. Sánchez, M. Büttiker, Optimal energy quanta to current conversion, PRB 83, 085428 (2011) [2] B. Sothmann, R. Sánchez, A. N. Jordan, M. Büttiker, Rectification of thermal fluctuations in a chaotic cavity heat engine, PRB 85, 205301 (2012) [3] B. Sothmann, M. Büttiker, Magnon-driven quantum-dot heat engine, EPL 99 27001 (2012)
Tuesday Electron refrigeration by nonadiabatic pumping and related questions on quantum cooling Fernando Sols Universidad Complutense de Madrid Some features of nonadiabatic electron heat pumps are studied and connected to general questions on quantum cooling [1,2]. Inelastic reflection is shown to contribute to heating if the external driving signal is time symmetric. Within the tunneling limit, it is shown that electron cooling still occurs if the coherent ac source is replaced by a sufficiently hot thermal bath. A comparison with related refrigeration setups is presented [3,4]. The quantum of cooling power (πk B T) 2 /6h$ is shown to be an upper limit to the cooling rate per transport channel in the presence of an arbitrary driving signal. The question is addressed of whether there is a universal limit to the cooling rate of a quantum system. [1] M. Rey, M. Strass, S. Kohler, P. Hänggi, F. Sols. Nonadiabatic electron heat pump, Phys. Rev. B 76, 085337 (2007). [2] F. Sols. Aspects of quantum cooling in electron and atom systems, Physica E 42, 466 (2010), Proc. FQMT’08. [3] J.P. Pekola, F.W.J. Hekking. Normal-Metal-Superconductor Tunnel Junction as a Brownian Refrigerator, Phys. Rev. Lett. 98, 210604 (2007). [4] B. Cleuren, B. Rutten, C. Van den Broeck. Cooling by Heating: Refrigeration Powered by Photons, Phys. Rev. Lett. 108, 120603 (2012). __________________________________________________________________________ Giant thermopower and figure of merit in single-molecule junctions Colin Lambert Department of Physics, Lancaster University, Lancaster, UK, LA1 4YB Single molecules connected to nanogap electrodes provide an opportunity for tuning electrical and thermoelectrical properties at the sub-nanometre scale. In this talk I shall present a study of the electronic contribution to thermopower S and the dimensionless figure of merit ZT in molecules sandwiched between gold electrodes. I shall show that for molecules with pendant groups, the shape of the transmission coefficient can be modified by Fano resonances near the Fermi energy, which can be tuned to produce huge increases in S and ZT. Tuning of transmission resonances can also be achieved by varying the coupling between molecular-scale structures. As an example, results will be presented for electron transport through single and double C60s. It will be shown that the thermopower and figure of merit for the latter is enhanced, compared with the former. [1] Giant thermopower and figure of merit in single-molecule devices, C. M. Finch, V. M. García-Suárez, and C. J. Lambert, Phys. Rev. B 79, 033405 (2009) [2] Control of electron transport through Fano resonances in molecular wires, T.A. Papadopoulos, I.M. Grace and C.J. Lambert, Phys. Rev. B 74 193306 (2006)
Page 1 and 2: 2012 22 Octobre 27 Octobre WORKSHOP
Page 3 and 4: Afternoon Morning Timetable Monday
Page 5 and 6: 15h50 - 16h20 Coffee Break 16h20 -
Page 7 and 8: Monday Abstracts Monday, October 22
Page 9 and 10: Monday Single-Electron Tunneling an
Page 11 and 12: Tuesday Tuesday, October 23 Random-
Page 13: Tuesday the energy level spacings a
Page 17 and 18: Wednesday [4] K. Saito, G. Benenti,
Page 19 and 20: Thursday [3] B. A. Bernevig, T. L.
Page 21 and 22: Thursday Electronic standing waves
Page 23 and 24: Friday Nanoscale inhomogeneities in
Page 25 and 26: Friday Electron focusing in graphem
Page 27 and 28: Friday molecules. We explain the or
Page 29 and 30: Posters Posters Ab-initio study of
Page 31 and 32: Posters Nonclassical photon-pair pr

nanoelectronics - Institut d'Études Scientifiques de Cargèse (IESC)

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