Fluctuation-Dissipative Phenomena in a Narrow Superconducting Channel Carrying Current Below Critical

TL;DR

This paper develops a theory for thermal fluctuation-induced dissipation in narrow superconducting channels near the critical temperature, explaining the broadening of the resistive transition through activation energy dependence on current.

Contribution

It introduces a new model linking activation energy to current in superconducting channels, aligning theoretical predictions with experimental observations.

Findings

Activation energy scales as (1-J/Jc)^(5/4) near critical current

The model explains the discrepancy between theory and experiment in transition broadening

Voltage as a function of temperature and bias current is derived

Abstract

The theory of current transport in a narrow superconducting channel accounting for thermal fluctuations is developed. These fluctuations result in the appearance of small but finite dissipation in the sample. The value of corresponding voltage is found as the function of temperature (close to transition temperature) and arbitrary bias current. It is demonstrated that the value of the activation energy (exponential factor in the Arrenius law) when current approaches to the critical one is proportional to (1-J/Jc)^(5/4). This result is in concordance with the one for the affine phenomenon of the Josephson current decay due to the thermal phase fluctuations, where the activation energy proportional (1-J/J_c)^(3/2)(the difference in the exponents is related to the additional current dependence of the order parameter). Found dependence of the activation energy on current explains the enormous discrepancy between the theoretically predicted before and the experimentally observed broadening of the resistive transition.