Reversal of Nonlocal Vortex Motion in the Regime of Strong Nonequilibrium

TL;DR

This paper explores nonlocal vortex motion in a-NbGe nanostructures, revealing sign reversals of nonlocal voltage driven by high currents, explained by nonequilibrium magnetization and electron heating effects.

Contribution

It uncovers a novel reversal of nonlocal vortex motion driven by strong nonequilibrium effects in superconducting nanostructures.

Findings

Sign reversals of nonlocal voltage at high currents

Dependence of sign reversal on temperature and current polarity

Quantitative explanation via nonequilibrium magnetization and electron heating

Abstract

We investigate nonlocal vortex motion in weakly pinning a-NbGe nanostructures, which is driven by a transport current I and remotely detected as a nonlocal voltage Vnl. At high I, the measured Vnl exhibits dramatic sign reversals that at low and high temperatures T occur for opposite polarities of I. The sign of Vnl becomes independent of that of the drive current at large abs(I). These unusual effects can be nearly quantitatively explained by a novel enhancement of magnetization, arising from a nonequilibrium distribution of quasiparticles at high T, and a Nernst-like effect resulting from local electron heating at low T.