Fluctuation conductivity of disordered superconductors in magnetic fields

TL;DR

This paper derives analytic formulas for fluctuation corrections to the conductivity of disordered superconductors in magnetic fields, covering the entire metallic phase and analyzing effects like non-monotonous magnetoresistance.

Contribution

It provides a comprehensive kinetic equation approach to fluctuation conductivity in disordered superconductors under magnetic fields, extending previous diagrammatic methods.

Findings

Analytic expressions valid across the metallic phase

Detailed comparison with diagrammatic perturbation theory

Identification of angle-dependent non-monotonous magnetoresistance

Abstract

We calculate fluctuation corrections to the longitudinal conductivity of disordered superconductors subject to an external magnetic field. We derive analytic expressions that are valid in the entire metallic part of the temperature-magnetic field phase diagram as long as the effect of the magnetic field on the spin degrees of freedom of the electrons may be neglected. Our calculations are based on a kinetic equation approach. For the special case of superconducting films and wires in parallel magnetic fields we perform a detailed comparison with results that were previously obtained with diagrammatic perturbation theory in the imaginary time formalism. As an application, we study the fluctuation conductivity of films in tilted magnetic fields with a special focus on the low-temperature regime. We present a detailed discussion of the phenomenon of the non-monotonous magnetoresistance and find that it displays a pronounced dependence on the tilting angle.