A correlation between energy gap, critical current density and relaxation of a superconductor

TL;DR

This paper investigates how energy gap, critical current density, and relaxation times in superconductors are interconnected, emphasizing the influence of temperature proximity to the critical point and using numerical simulations to explore these relationships.

Contribution

It introduces a quantitative analysis of the correlation between energy gap, critical current density, and relaxation times in superconductors, based on thermodynamic and heat transfer principles.

Findings

Relaxation times increase as temperature approaches the critical point.

Energy gap and critical current density are tightly linked to relaxation rates.

Numerical simulations suggest specific quantitative relationships among these properties.

Abstract

Superconductors like other solids cannot relax instantaneously from excited states to thermodynamic equilibrium. In this paper, relaxation from thermal excitations is investigated, like after absorption of radiation or, under conductor movement, release and transformation of mechanical tension to thermal energy. Relaxation proceeds within finite periods of time the length of which increases the more strongly the closer the superconductor temperature has already approached its critical value. Properties of many-particle systems (as explained, by an analogy to nuclear physics), basic thermodynamic considerations (temperature uniquely defined under solely equilibrium condition) and standard, multi-component heat transfer principles (solid conduction plus radiation in thin films) are applied as tools to prove this expectation. Energy gap, superconductor critical current density and critical temperature, as a result, are tightly related to relaxation rates and relaxation times of the superconductor electron system. By numerical simulations, an attempt is made to find a quantitative correlation of these properties in a thin film superconductor.