Dynamic Aspects of Strong Pinning

TL;DR

This paper analyzes the current-voltage behavior of type II superconductors with strong pinning centers, deriving a generic flux-flow characteristic and exploring the effects of defect density and pinning strength.

Contribution

It introduces a unified framework for understanding flux-flow in superconductors with strong pinning, bridging single-pin and collective pinning regimes.

Findings

Derives a generic current-voltage characteristic with a shifted linear flux-flow branch.

Identifies the dependence of onset behavior on the Labusch parameter $7$.

Reproduces collective pinning results in the weak pinning limit.

Abstract

We determine the current--voltage characteristic of type II superconductors in the presence of strong pinning centers. Focusing on a small density of defects, we derive a generic form for the characteristic with a linear flux-flow branch shifted by the critical current (excess-current characteristic). The details near onset, a hysteretic jump (for $\kappa \gg 1$) or a smooth velocity turn-on ($\kappa \to 1$), depend on the Labusch parameter $\kappa$ characterising the pinning centers. Pushing the single-pin analysis into the weak pinning domain, we reproduce the collective pinning results for the critical current.