Anomalous flux-flow dynamics in layered type-II superconductors at low temperatures

TL;DR

This paper investigates low-temperature vortex motion in layered type-II superconductors, revealing that dissipation is governed by Zener transitions between localized electronic states, leading to a new example of parametric energy level statistics.

Contribution

It introduces a novel mechanism for vortex-induced dissipation involving Zener transitions and connects vortex dynamics to random matrix theory class C.

Findings

Flux-flow conductivity is slightly lower than quasiclassical predictions.

Conductivity increases slowly with electric field.

Vortex motion exhibits a new type of parametric energy level statistics.

Abstract

Low-temperature dissipation due to vortex motion in strongly anisotropic type-II superconductors with a moderate disorder ($\Delta^2/E_F \ll \hbar/\tau \ll \Delta$) is shown to be determined by the Zener-type transitions between the localized electronic states in the vortex core. Statistics of these levels is described by the random matrix ensemble of the class C defined recently by Atland and Zirnbauer [cond-mat/9602137], so the vortex motion leads naturally to the new example of a parametric statistics of energy levels. The flux-flow conductivity $\sigma_{xx}$ is a bit lower than the quasiclassical one and {\it grows} slowly with the increase of the electric field.