Energy Relaxation at a Hot-Electron Vortex Instability

TL;DR

This paper investigates the energy relaxation mechanisms in superconducting films experiencing vortex instability, showing that electron heating and energy transfer rates are key to understanding the observed high vortex velocities.

Contribution

It provides a detailed analysis of energy flow assumptions, calculates energy transfer rates, and estimates relaxation times and phonon mean free path relevant to vortex instability.

Findings

Electronic temperature reaches near Tc at instability

Calculated energy relaxation times match experimental data

Phonon mean free path influences energy flow

Abstract

At high dissipation levels, vortex motion in a superconducting film has been observed to become unstable at a certain critical vortex velocity v*. At substrate temperatures substantially below Tc, the observed behavior can be accounted for by a model in which the electrons reach an elevated temperature relative to the phonons and the substrate. Here we examine the underlying assumptions concerning energy flow and relaxation times in this model. A calculation of the rate of energy transfer from the electron gas to the lattice finds that at the instability, the electronic temperature reaches a very high value close to the critical temperature. Our calculated energy relaxation times are consistent with those deduced from the experiments. We also estimate the phonon mean free path and assess its effect on the flow of energy in the film.