Diversity of flux avalanche patterns in superconducting films

TL;DR

This study uses numerical simulations to explore how different thermal and electromagnetic parameters influence the diverse flux avalanche patterns in superconducting films, revealing key factors that control their morphology.

Contribution

It introduces a comprehensive simulation model that systematically analyzes the effects of thermal and electromagnetic parameters on flux avalanche morphologies in superconducting films.

Findings

Branching is suppressed by lateral heat diffusion.

Large Joule heating increases avalanche branching.

Heat removal to substrate limits avalanche size.

Abstract

The variety of morphologies in flux patterns created by thermomagnetic dendritic avalanches in type-II superconducting films is investigated using numerical simulations. The avalanches are triggered by introducing a hot spot at the edge of a strip-shaped sample, which is initially prepared in a partially penetrated Bean critical state by slowly ramping the transversely applied magnetic field. The simulation scheme is based on a model accounting for the nonlinear and nonlocal electrodynamics of superconductors in the transverse geometry. By systematically varying the parameters representing the Joule heating, heat conduction in the film, and heat transfer to the substrate, a wide variety of avalanche patterns is formed, and quantitative characterization of areal extension, branch width etc. is made. The results show that branching is suppressed by the lateral heat diffusion, while large Joule heating gives many branches, and heat removal into the substrate limits the areal size. The morphology shows significant dependence also on the initial flux penetration depth.