Vortex interactions in presence of a soft magnetic film

TL;DR

This paper theoretically investigates how a soft magnetic film influences vortex interactions in a thin film superconductor, revealing a distance-dependent switch from attraction to repulsion between vortices.

Contribution

It introduces a model showing that soft magnetic films can alter vortex interactions, making them attractive at short range and repulsive at long range, unlike in the absence of such films.

Findings

Vortex interactions become attractive at short distances due to the magnetic film.

The magnetic film modifies the vortex fields and interactions.

Vortex interactions are repulsive at larger distances, consistent with traditional behavior.

Abstract

We study theoretically the behavior of vortices in a thin film superconductor placed close to a soft magnetic film. It is shown that the field from the vortex induces a magnetization distribution in the soft magnetic film, thus modifying the fields and vortex interactions. We suggest that the interaction between two otherwise identical vortices is attractive at short distances, but repulsive at larger distances. This is in contrast to the case without the soft magnetic film, where the force is always repulsive.