Optical conductivity in non-equilibrium d-wave superconductors

TL;DR

This paper investigates how non-equilibrium quasiparticle distributions affect the optical conductivity in d-wave superconductors, comparing two simplified models originally used for s-wave superconductors.

Contribution

It extends existing models to d-wave superconductors and compares two different approaches for describing non-equilibrium quasiparticles.

Findings

Qualitative similarities in the models' results.

Model-specific features identified.

Insights into non-equilibrium effects on optical conductivity.

Abstract

We consider the optical conductivity of a d-wave BCS superconductor in the presence of a non-equilibrium distribution of excess quasiparticles. Two different simplified models used in the past for the s-wave case are considered and results compared. In the $T^\ast$-model of Parker the excess quasiparticles are assumed to be in a thermal distribution at some temperature $T^\ast$ larger than the equilibrium sample temperature. In the $\mu^\ast$- model of Owen and Scalapino a chemical potential is introduced to accommodate the excess quasiparticles. Some of the results obtained are specific to the model, most are qualitatively similar in both.