Phase Slip Avalanches in Small Superconductors

TL;DR

This paper investigates phase slip avalanches in quasi-1D superconductors, revealing a new mechanism that limits critical current and induces a topological transition, supported by analytical derivations and experimental data.

Contribution

It introduces a novel understanding of phase slip avalanches in thin superconducting films, deriving an exact analytical expression for critical current considering temperature and width.

Findings

Avalanche of phase slips limits critical current in thin films.

Derived an exact formula for critical current as a function of temperature and width.

Results agree with experimental data on MgB₂ thin films.

Abstract

We study the effect of phase slips in a quasi 1d superconducting channel along which a current flows and report a new phenomenon where an avalanche of phase slips occurs. This limits the critical current in thin films and wires and drives the system to a topological phase transition at a temperature lower than the bulk critical temperature. We describe the mechanism of such a catastrophic phase slip avalanche and, following Kosterlitz and Thouless, we use group renormalization techniques to derive an exact analytical expression for the critical current as a function of film width and temperature. Our results are in very good agreement with, and reproduce, the available experimental data on superconducting MgB$_2$ thin films. The phenomenon we describe is very general and can be used in the construction of new devices where the superconducting state can coexist with the normal state.