Weak localization correction to linear absorption in conventional superconductors

TL;DR

This paper investigates how weak localization effects influence the linear absorption spectrum in disordered s-wave superconductors, revealing significant suppression related to electron interactions and diffusive motion.

Contribution

It introduces a vertex correction method consistent with weak localization to analyze the absorption spectrum in disordered superconductors, highlighting the impact of electron interactions.

Findings

Weak localization suppresses absorption across the superconducting gap.

The suppression is more pronounced than thermal excitation effects.

Absorption ratio varies significantly near twice the gap energy.

Abstract

The weak localization effect on a linear absorption spectrum is investigated for disordered s-wave superconductors. The vertex correction is incorporated into the response function in a way that is consistent with the weak localization correction to a one-particle spectrum. The effect of interactions between electrons enhanced by their diffusive motion makes a major contribution to the correction term. Numerical calculations show that the weak localization effect suppresses the absorption by the excitation across the gap to a greater extent than that by thermal excitation, which is a similar tendency to the results of experiments. The ratio of the linear absorption with vertex corrections to that without the corrections shows a large variation at the frequency that is around twice the energy of the superconducting gap. This behavior represents a relationship between the weak localization effect on the linear absorption and that on the one-particle spectrum.