Onset of dendritic flux avalanches in superconducting films

TL;DR

This paper compares experimental magneto-optical imaging data with a thermo-magnetic model to accurately predict the onset of dendritic flux avalanches in superconducting films, demonstrating the model's effectiveness across different materials.

Contribution

It validates a recent thermo-magnetic model for predicting dendritic flux instability onset in superconducting films through experimental data analysis.

Findings

The model accurately predicts the magnetic field at instability onset.

The onset field depends on temperature and sample size as described by the model.

Good agreement with experimental data for MgB2 and Nb samples.

Abstract

We report a detailed comparison of experimental data and theoretical predictions for the dendritic flux instability, believed to be a generic behavior of type-II superconducting films. It is shown that a thermo-magnetic model published very recently [Phys. Rev. B 73, 014512 (2006)] gives an excellent quantitative description of key features like the instability onset (first dendrite appearance) magnetic field, and how the onset field depends on both temperature and sample size. The measurements were made using magneto-optical imaging on a series of different strip-shaped samples of MgB2. Excellent agreement is also obtained by reanalyzing data previously published for Nb.