Signatures of the nematic ordering transitions in the thermal conductivity of d-wave superconductors

TL;DR

This paper investigates how the nematic quantum phase transition in d-wave superconductors affects thermal conductivity, revealing signatures of anisotropic fixed points and the influence of disorder and interactions.

Contribution

It introduces a kinetic approach to identify thermal transport signatures of the nematic transition and analyzes the effects of disorder and interactions on these signatures.

Findings

Thermal conductivity is enhanced near the nematic critical point.

Logarithmic signatures indicate approach to anisotropic fixed point.

Disorder and interactions significantly influence thermal transport measurements.

Abstract

We study experimental signatures of the Ising nematic quantum phase transition in d-wave superconductors, associated with the change of lattice symmetry from tetragonal to orthorhombic in the superconducting state. The characteristic feature of this transition is that the ratio between the Fermi velocity $v_F$ and gap velocity $v_\Delta$ flows to a maximally anisotropic fixed point, i.e. the renormalization group fixed point is situated at (v_\Delta/v_F)^*=0$. Our main point is that the logarithmic approach to this fixed point has visible signatures in the thermal transport. The analysis of the quasiparticle contribution to the thermal transport is carried out in the framework of a kinetic approach, which shows that the thermal conductivity is enhanced near the nematic critical point. Another aspect of our study is the interplay of dilute disorder and electronic interactions in the measured thermal transport coefficients.