Thermoelectric transport near pair breaking quantum phase transition out of d-wave superconductivity

TL;DR

This paper investigates the transport properties near a quantum phase transition from d-wave superconductivity to a diffusive metal, revealing violations of conventional laws and introducing a Langevin formalism for critical dynamics.

Contribution

It provides a detailed analysis of electric, thermal, and thermoelectric conductivities near the transition, highlighting non-Fermi liquid behavior and developing a new theoretical approach.

Findings

Violation of Wiedemann-Franz law near the transition

Non-vanishing dc thermoelectric conductivity at low temperatures

Development of a Langevin equation formalism for critical dynamics

Abstract

We study electric, thermal, and thermoelectric conductivities in the vicinity of a z=2 superconductor-diffusive metal transition in two dimensions, both in the high and low frequency limits. We find violation of the Wiedemann-Franz law and a dc thermoelectric conductivity $\alpha$ that does not vanish at low temperatures, in contrast to Fermi liquids. We introduce a Langevin equation formalism to study critical dynamics over a broad region surrounding the quantum critical point.