Estados de vórtices em supercondutores mesoscópicos do tipo-II com espessura finita

Abstract

In search for better superconducting characteristics, we studied theoretically samples with dimensions close to the London penetration deph and coeherence lenght. For such dimensions, superconductors of types I and II showed different responses to magnetic field. We found a effective Ginzburg-Landau parameter, so that for very small thickness (tending to zero), superconductors behave as type-II superconductors, with mixed state. We studied the energy in a mixed state, where the vortex entry reduce the energy of the superconductor. In this work, the two Ginzburg-Landau equations were solved numerically, the first by a relaxation method, where the order parameter function is relaxed from an initial condition until convergece is achieved. For the second, we used the Fourier transform technique, to help us to solve it more easily in reciprocal space. To solve them numerically, we use the linkvariables method with gauge invariance, adapted for finite difference algorithm. The study of the vortices dynamics have been made here for type-II superconductors with different thicknesses, square symetry and different magnetic fields.