Little-Parks effect in a superconducting loop with magnetic dot

TL;DR

This study investigates how a magnetic dot influences superconductivity in a mesoscopic aluminum loop, revealing asymmetric phase boundaries and a maximum critical temperature at a finite, antiparallel magnetic field, supported by experimental and theoretical agreement.

Contribution

It demonstrates the impact of a magnetic dot on superconducting phase boundaries, highlighting the asymmetry and the optimal magnetic field conditions for superconductivity.

Findings

Asymmetric Tc(B) phase boundary due to magnetic dot

Maximum critical temperature at finite antiparallel magnetic field

Good agreement between experimental data and theoretical model

Abstract

We have studied the nucleation of superconductivity in a mesoscopic Al loop, enclosing magnetic dot with perpendicular magnetization. The superconducting phase boundary Tc(B), determined from transport measurements, is asymmetric with respect to the polarity of an applied magnetic field. The maximum critical temperature has been found for a finite applied magnetic field, which is antiparallel to the magnetization of the dot. Theoretical phase boundary shows a good agreement with the experimental data.