Mesoscopic field and current compensator based on a hybrid superconductor-ferromagnet structure

TL;DR

This paper demonstrates enhanced superconductivity in a hybrid superconductor-ferromagnet structure, where the ferromagnet screens magnetic fields and induces current flows, allowing superconductivity to withstand higher magnetic fields and currents.

Contribution

It introduces a novel hybrid structure that enhances superconductivity through magnetic field screening and current compensation effects, revealing new mechanisms for superconductivity resilience.

Findings

Superconductivity persists at higher magnetic fields due to ferromagnet screening.

Induced opposite current flows in the superconductor enhance current-carrying capacity.

Transitions to normal state involve vortex-antivortex and phase-slip phenomena.

Abstract

A rather general enhancement of superconductivity is demonstrated in a hybrid structure consisting of submicron superconducting (SC) sample combined with an in-plane ferromagnet (FM). The superconducting state resists much higher applied magnetic fields for both perpendicular polarities, as applied field is screened by the FM. In addition, FM induces (in the perpendicular direction to its moment) two opposite current-flows in the SC plane, under and aside the magnet, respectively. Due to the compensation effects, superconductivity persists up to higher applied currents. With increasing current, the sample undergoes SC-"resistive"-normal state transitions through a mixture of vortex-antivortex and phase-slip phenomena.