Thermomagnetic instabilities in Nb films deposited on glass substrates

TL;DR

This study investigates thermomagnetic instabilities in niobium films on glass, using magneto-optical imaging to analyze flux avalanches and compare experimental results with theoretical models, revealing key thermal and superconducting parameters.

Contribution

It provides a systematic experimental and theoretical analysis of flux avalanches and thermomagnetic instabilities in Nb films, including the effects of thickness and temperature.

Findings

Identification of threshold magnetic fields for instability onset

Correlation between flux penetration depth and film parameters

Quantitative evaluation of thermal and superconducting properties

Abstract

In this work, we provide a systematic study of the magnetic field penetration process and avalanche formation in niobium films of different thicknesses deposited on glass substrates. The research was carried out by means of direct visualization of the magnetic flux using magneto-optical imaging. The experimental data were compared with theoretical predictions for the development of thermomagnetic instabilities in the form of finger or dendritic flux avalanches in thin films. Analysis of the temperature and thickness dependence of threshold magnetic field at which superconductor first becomes unstable, as well as the flux penetration depth corresponding to this field allows the evaluation of the thermal and superconducting parameters of the studied films, such as heat transfer coefficient across the film-substrate boundary, thermal conductivity, critical current density.