Little-Parks Oscillations in Hybrid Ferromagnet-Superconductor Systems

TL;DR

This paper investigates how exchange fields in superconductor/ferromagnet hybrids influence Little-Parks oscillations and superconducting state transitions, revealing potential increases in critical temperature and effects of interface transparency.

Contribution

It introduces a theoretical analysis of superconductivity nucleation in S/F hybrids considering exchange fields and interface transparency, highlighting their impact on vorticity states and critical temperature.

Findings

Exchange field induces switching between vorticity states.

Critical temperature can increase due to exchange field effects.

S/F interface transparency affects higher vorticity state realization.

Abstract

On the basis of of linearized Usadel equations we consider superconductivity nucleation in multiply connected mesoscopic superconductor/ferromagnet hybrids such as thin-walled superconducting cylinders placed in electrical contact with a ferromagnetic metal. We study the interplay between the oscillations of $T_c$ due to the Little--Parks effect and the oscillations due to the exchange field. We demonstrate that the exchange field provokes the switching between the superconducting states with different vorticities and this may result in the increase the critical temperature of the superconducting transition in the magnetic field. Moreover we analyse the influence of the S/F transparency on the realisation of the states with higher vorticities.