Enhancing the effective critical current density in a Nb superconducting thin film by cooling in an inhomogeneous magnetic field

TL;DR

This study demonstrates that cooling a Nb superconducting thin film in an inhomogeneous magnetic field enhances its critical current density by improving its magnetic shielding, with implications for superconducting device performance.

Contribution

The paper introduces a novel method of cooling in an inhomogeneous magnetic field to increase the effective critical current density in superconducting thin films.

Findings

Inhomogeneous magnetic field cooling enhances screening capacity.

Vortex-antivortex interactions influence magnetic flux penetration.

Initial vortex states reduce flux front penetration depth.

Abstract

Quantitative magneto-optical imaging of a type-II superconductor thin film cooled under zero, homogeneous, and inhomogeneous applied magnetic fields, indicates that the latter procedure leads to an enhancement of the screening capacity. Such an observation is corroborated by both B-independent and B-dependent critical state model analyses. Furthermore, repulsive (attractive) vortex-(anti)vortex interactions were found to have a decisive role in the shielding ability, with initial states prepared with vortices resulting in a shorter magnetic flux front penetration depth than those prepared with antivortices. The proposed strategy could be implemented to boost the performance of thin superconducting devices.