Steps in the Negative-Differential-Conductivity Regime of a Superconductor

TL;DR

This paper investigates the negative differential conductivity regime in Y1Ba2Cu3O(7-delta) superconducting films, revealing a staircase pattern in current-voltage characteristics linked to vortex dynamics and phase formation.

Contribution

It introduces a novel interpretation of the staircase pattern as resulting from nucleation of quantized vortex distortions in the flux flow regime.

Findings

Observation of negative differential conductivity in superconducting films.

Identification of staircase-like patterns in the current-voltage curves.

Attribution of steps to nucleation of quantized vortex distortions.

Abstract

Current-voltage characteristics were measured in the mixed state of Y1Ba2Cu3O(7-delta) superconducting films in the regime where flux flow becomes unstable and the differential conductivity dj/dE becomes negative. Under conditions where its negative slope is steep, the j(E) curve develops a pronounced staircase like pattern. We attribute the steps in j(E) to the formation of a dynamical phase consisting of the succesive nucleation of quantized distortions in the local vortex velocity and flux distribution within the moving flux matter.