Asymmetric Avalanches in the Condensate of a Zeeman-limited Superconductor

TL;DR

This study investigates the non-equilibrium behavior of disordered superconducting aluminum films under high Zeeman fields, revealing asymmetric avalanche-like condensate collapses and continuous recoveries, indicating inhomogeneous order parameters.

Contribution

It demonstrates the first observation of asymmetric avalanches in the Zeeman-driven transition of disordered superconductors, highlighting non-homogeneous order parameter dynamics.

Findings

Avalanche-like condensate collapses on the superheating branch.

Continuous transition back into superconducting phase.

Evidence of inhomogeneous order parameter in the hysteretic regime.

Abstract

We report the non-equilibrium behavior of disordered superconducting Al films in high Zeeman fields. We have measured the tunneling density of states of the films through the first-order Zeeman critical field transition. We find that films with sheet resistances of a few hundred ohms exhibit large avalanche-like collapses of the condensate on the superheating branch of the critical field hysteresis loop. In contrast, the transition back into the superconducting phase (i.e., along the supercooling branch) is always continuous. The fact that the condensate follows an unstable trajectory to the normal state suggests that the order parameter in the hysteretic regime is not homogeneous.