Vortex microavalanches in superconducting Pb thin films

TL;DR

This study investigates vortex microavalanches in superconducting Pb thin films, revealing temperature-dependent flux behavior, dendritic flux protrusions, and the influence of defects on avalanche dynamics.

Contribution

It provides new insights into the temperature-dependent flux penetration and the role of defects in vortex avalanches in superconducting thin films.

Findings

Flux jumps increase then disappear near 0.7Tc

Avalanches resemble dendritic flux protrusions

Defect structure influences avalanche reproducibility

Abstract

Local magnetization measurements on 100 nm type-II superconducting Pb thin films show that flux penetration changes qualitatively with temperature. Small flux jumps at the lowest temperatures gradually increase in size, then disappear near T = 0.7Tc. Comparison with other experiments suggests that the avalanches correspond to dendritic flux protrusions. Reproducibility of the first flux jumps in a decreasing magnetic field indicates a role for defect structure in determining avalanches. We also find a temperature-independent final magnetization after flux jumps, analogous to the angle of repose of a sandpile.