Download Abstracts Book - DF-UFPE Pessoal

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