The Critical Current of Disordered Superconductors near T=0

TL;DR

This paper investigates the critical current in disordered superconductors at low temperatures, demonstrating that electron overheating due to thermal decoupling explains the observed current-voltage behavior.

Contribution

It introduces a heat-balance model to accurately predict critical currents, emphasizing the role of electron overheating over microscopic details.

Findings

Electron overheating explains the critical current behavior.

Heat-balance model accurately predicts experimental critical currents.

Universal approach applicable to diverse systems.

Abstract

An increasing current through a superconductor can result in a discontinuous increase in the differential resistance at the critical current. This critical current is typically associated either with breaking of Cooper-pairs (de-pairing) or with a collective motion of vortices (de-pinning). In this work we measure superconducting amorphous indium oxide films at low temperatures and high magnetic fields. Using heat-balance considerations we demonstrate that the current-voltage characteristics are well explained by electron overheating that occurs due to the thermal decoupling of the electrons from the host phonons. As a result the electrons overheat to a significantly higher temperature than that of the lattice. By solving the heat-balance equation we are able to accurately predict the critical currents in a variety of experimental conditions. The heat-balance approach stems directly from energy conservation. As such it is universal and applies to diverse situations from critical currents in superconductors to climate bi-stabilities that can initiate another ice-age. One disadvantage of the universal nature of this approach is that it is insensitive to the microscopic details of the system, which limits our ability to draw conclusions regarding the initial departure from equilibrium.