Linear response and collective oscillations in superconductors with d-wave pairing

TL;DR

This paper derives simple equations for the linear electromagnetic response of layered d-wave superconductors, revealing how different electric field responses depend on relaxation processes and damping of plasma oscillations.

Contribution

It introduces transparent equations for the linear response of layered d-wave superconductors using quasiclassical kinetic theory, highlighting the distinct frequency dependencies of responses to different electric fields.

Findings

Response to solenoidal field limited by momentum relaxation

Response to potential field depends on branch imbalance relaxation

Carlson-Goldman mode is overdamped in d-wave superconductors

Abstract

Simple and physically transparent equations for the linear response of layered superconductors with d-wave symmetry of the order parameter are derived by means of the quasiclassic kinetic theory of superconductivity. Responses to solenoidal and potential electric fields have different frequency dependencies. The conductivity describing the response to the solenoidal field is limited by the momentum relaxation, like in a normal metal. The response to the potential electric field depends, in addition, on the branch imbalance relaxation rate. The damping of plasma oscillations of superconducting electrons is determined by dielectric relaxation and is small. Relaxation of branch imbalance determined by elastic scattering is large enough to make the Carlson-Goldman mode in d-wave superconductors overdamped.