Transport theory of superconductors with singular interaction corrections

TL;DR

This paper investigates how strong fluctuations and interactions near the critical point affect superconductors' transport properties, revealing a new regime with more singular fluctuation-induced conductivity contributions.

Contribution

It introduces a theoretical framework for understanding the interplay of fluctuation effects and interactions, identifying a novel regime with enhanced singularity in conductivity near the critical point.

Findings

Dynamic Aslamazov-Larkin term dominates the singularity

Quantum pair-breaking suppresses superconductivity

Magnetoconductivity measurements can probe nonlinear fluctuations

Abstract

We study effects of strong fluctuations on the transport properties of superconductors near the classical critical point. In this regime conductivity is set by the delicate interplay of two competing effects. The first is that strong electron-electron interactions in the Cooper channel increase the life-time of fluctuation Cooper pairs and thus enhance conductivity. On the other hand, quantum pair-breaking effects tend to suppress superconductivity. An interplay between these processes defines new regime where fluctuation induced transport becomes more singular. The most singular contributions to the conductivity stem from the dynamic Aslamazov-Larkin term, and novel Maki-Thompson and interference corrections. The crossover temperature from weakly to strongly fluctuating regime is generated self-consistently as the result of scattering on dynamic variations of the order parameter. We suggest that the way to probe nonlinear-fluctuations in superconductors is by magnetoconductivity measurements in the perpendicular field.