Vortex-antivortex nucleation in magnetically nanotextured superconductors: Magnetic-field-driven and thermal scenarios

TL;DR

This paper predicts two new mechanisms for vortex-antivortex pair nucleation in magnetically nanostructured superconductors, involving magnetic fields and thermal effects, with implications for superconducting phase behavior.

Contribution

It introduces novel vortex-antivortex nucleation mechanisms in superconductor/ferromagnet hybrids using Ginzburg-Landau theory, including magnetic-field-driven and thermal scenarios.

Findings

Vortex-antivortex pairs can nucleate under external magnetic fields.

Thermal effects induce vortex-antivortex configurations.

New Little-Parks oscillations observed in magnetization-temperature phase boundary.

Abstract

Within the Ginzburg-Landau formalism, we predict two novel mechanisms of vortex-antivortex nucleation in a magnetically nanostructured superconductor. Although counterintuitive, nucleation of vortex-antivortex pairs can be activated in a superconducting (SC) film covered by arrays of submicron ferromagnets (FMs) when exposed to an external homogeneous magnetic field. In another scenario, we predict the thermal induction of vortex-antivortex configurations in SC/FM samples. This phenomenon leads to a new type of Little-Parks oscillations of the FM magnetization-temperature phase boundary of the superconducting film.