Little-Parks effect and multiquanta vortices in a hybrid superconductor--ferromagnet system

TL;DR

This paper explores how ferromagnetic nanoparticles influence superconducting thin films, revealing oscillations in critical temperature and multiquanta vortex formations through analytical and numerical methods.

Contribution

It introduces a phenomenological Ginzburg-Landau model to analyze the phase diagram of superconductor-ferromagnet systems, highlighting the Little-Parks effect and multiquanta vortices.

Findings

Oscillatory critical temperature dependence on magnetic field

Formation of multiquanta vortex structures

Analytical and numerical validation of phenomena

Abstract

Within the phenomenological Ginzburg-Landau theory we investigate the phase diagram of a thin superconducting film with ferromagnetic nanoparticles. We study the oscillatory dependence of the critical temperature on an external magnetic field similar to the Little-Parks effect and formation of multiquantum vortex structures. The structure of a superconducting state is studied both analytically and numerically.