Superconducting films with antidot arrays - novel behavior of the critical current

TL;DR

This paper reports a novel reversal of the critical current density peaks in perforated superconducting films, caused by vortex caging effects, which can be tuned by geometry and material properties, leading to step-like behavior.

Contribution

It reveals a new phenomenon where critical current peaks increase with magnetic field under specific conditions, contrasting previous observations, and explains it through vortex caging and material parameters.

Findings

Reversal of critical current peak behavior at matching fields.

Vortex caging causes enhanced vortex pinning.

Step-like critical current behavior predicted for type-I superconductors.

Abstract

Novel behavior of the critical current density $j_{c}$ of a regularly perforated superconducting film is found, as a function of applied magnetic field $H$. Previously pronounced peaks of $j_{c}$ at matching fields were always found to decrease with increasing $H$. Here we found a {\it reversal of this behavior} for particular geometrical parameters of the antidot lattice and/or temperature. This new phenomenon is due to a strong ``caging'' of interstitial vortices between the pinned ones. We show that this vortex-vortex interaction can be further tailored by an appropriate choice of the superconducting material, described by the Ginzburg-Landau parameter $\kappa$. In effective type-I samples we predict that the peaks in $j_{c}(H)$ at the matching fields are transformed into a {\it step-like behavior}.