Large Thermoelectric Effects and Inelastic Scattering in Unconventional Superconductors

TL;DR

This paper investigates how impurity and inelastic scattering affect the thermoelectric coefficient in unconventional superconductors, revealing temperature-dependent suppression and recovery of thermoelectric effects linked to scattering mechanisms.

Contribution

It provides a detailed theoretical analysis of the impact of impurity and inelastic scattering on thermoelectric effects in strong-coupling d-wave superconductors, highlighting their temperature dependence.

Findings

Impurity scattering enhances thermoelectric coefficient below Tc.

Inelastic scattering suppresses thermoelectric effects just below Tc.

At low temperatures, thermoelectric coefficient recovers and is proportional to T.

Abstract

The thermoelectric coefficient $\eta(T)$ in unconventional superconductors is enhanced below $T_c$ by intermediate strength impurity scattering that is intrinsically particle-hole asymmetric. We compute $\eta(T)$ for a strong-coupling d-wave superconductor and investigate the effects of inelastic scattering originating from electron-boson interactions. We show that $\eta(T)$ is severely suppressed at temperatures just below $T_c$ by a particle-hole symmetric inelastic scattering rate. At lower temperatures inelastic scattering is frozen out and $\eta(T)$ recovers and regains its large amplitude. In the limit $T\to 0$, we have $\eta(T)\sim \eta_{0} T+{\cal O}[T^3]$, where the slope $\eta_{0}$ contains information about the Drude plasma frequency, the details of impurity scattering, and the change in effective mass by electron-boson interactions. In this limit $\eta(T)$ can be used as a probe, complementary to the universal heat and charge conductivities, in investigations of the nature of nodal quasiparticles.