Cascade dynamics of thermomagnetic avalanches in superconducting films with holes

TL;DR

This study investigates the rapid cascade behavior of thermomagnetic avalanches in superconducting films with holes, revealing how hole shape influences avalanche nucleation and propagation through numerical simulations and experimental imaging.

Contribution

It introduces a detailed numerical analysis of cascading avalanches in superconducting films with various hole geometries, supported by magneto-optical imaging evidence.

Findings

Holes with sharp corners frequently induce secondary avalanches.

Avalanches tend to nucleate at the corners of holes.

Numerical simulations align with experimental magneto-optical imaging results.

Abstract

The sub-microsecond dynamics of thermomagnetic avalanches in superconducting films with non-conducting holes (antidots) is considered. When such an avalanche reaches a hole, it is quickly filled with magnetic flux, and often its rim becomes unstable and a second avalanche is nucleated. In this work the time- and space-resolved behavior of such cascading avalanche behavior is determined using numerical simulations. Results are presented for films with holes of different shape. It is found that holes with sharp corners are those that most frequently create secondary avalanches, and they tend to nucleate in corners. Magneto-optical imaging of Nb films patterned with the same set of holes strongly supports the numerical results.