Frozen magnetic response in mesoscopics superconductors

Abstract

For a bulk type II superconducting sample at low temperature, the magnetic field can penetrate in the form of a single quantum fluxoid, for bulk samples this fluxoides are arranged in a hexagonal lattice, this so-called Shubnikov-Abrikosov state or vortex state and takes place between the first and the second critical thermodynamics magnetic fields. Under the first magnetic critical field is present the Meissner-Oschenfeld state. For mesoscopic samples, the magnetic response can present very interesting properties due the proximity effect of in-homogeneous boundary conditions and the presence of dots, anti-dots and/or impurities. The superconducting state in a mesoscopic sample with dot/anti-dot/dot/pillar/trench is calculated within the nonlinear Ginzburg-Landau equations. We predict that the critical magnetic fields and magnetization depends on strongly of the nature, geometry, size of the defects and the boundary conditions used.