Conductance switching and nonequilibrium phase coexistence in superconductors with intermediate bias

TL;DR

This study investigates nonequilibrium states in superconducting films under finite voltage bias, revealing phase coexistence and negative differential conductance, which are not observable with traditional current-bias methods.

Contribution

It demonstrates the existence of nonequilibrium phase coexistence and negative differential conductance in superconductors under finite bias, expanding understanding of superconducting state dynamics.

Findings

Observation of negative differential conductance features.

Detection of dissipative states with intermediate resistance.

Identification of phase coexistence under nonequilibrium conditions.

Abstract

Superconducting systems may display different types of nonequilibrium states depending on the specific constraints imposed for measurement. We probe current-voltage relations of three-dimensional superconducting films by allowing finite voltages to develop across their length. Our experiments reveal sharp features of negative differential conductance which highlight the validity of the principle of minimum entropy production at the critical current transition. We have observed dissipative states with resistances intermediate between those of superconducting and normal phases at zero applied magnetic field, indicating a phenomenon of phase coexistence under nonequilibrium conditions. The features of steady states reported here are not accessible in conventional transport experiments with current-biasing methods.