Vortex-antivortex configurations and their stability in mesoscopic superconducting square

TL;DR

This study solves the Ginzburg-Landau equation for mesoscopic square superconductors, revealing the existence and stability conditions of antivortex configurations across various parameters and highlighting differences from cylindrical samples.

Contribution

It provides a detailed analysis of antivortex stability in mesoscopic square superconductors using Ginzburg-Landau theory, extending understanding beyond cylindrical geometries.

Findings

Antivortex phase exists over a broad parameter range.

Giant vortex with vorticity m=3 is always unstable.

Reducing kappa does not stabilize antivortex states.

Abstract

We solve the Ginzburg-Landau equation (GLE) for the mesoscopic superconducting thin film of the square shape in the magnetic field for the wide range of the Ginzburg-Landau parameter 0.05< kappa. We focus on the region of the field where formation of the antivortex has been reported previously. We found that the phase with the antivortex exists in the broad range of parameters. When the coherence length decreases the topological phase transition to the phase with the same total vorticity and a reduced symmetry takes place. The giant vortex with the vorticity m=3 is found to be unstable for any field, xi/a and kappa. Reduction of kappa does not make the phase with antivortex more stable contrary to the case of the cylindric sample of the type I superconductor.