Thermal transport in two-dimensional nematic superconductors

Abstract

We study the thermal transport in a two-dimensional system with coexisting superconducting (SC) and nematic orders. We analyze the nature of the coexistence phase in a tight-binding square lattice where the nematic state is modelled as a d-wave Pomeranchuk-type instability and the feedback of the symmetry breaking nematic state on the SC order is accounted for by mixing of the s, d paring interaction. The electronic thermal conductivity is computed within the framework of Boltzmann kinetic theory where the impurity scattering collision integral is treated in the Born and unitary limits. We present qualitative, analytical, and numerical results that show that the heat transport properties of SC states emerging from a nematic background are quite distinct and depend on the degree of anisotropy of the SC gap induced by nematicity. We describe the influence of the Fermi surface topology, the van Hove singularities, and the presence or absence of zero-energy excitations in the coexistence phase on the the low-temperature behavior of the thermal conductivity. Our main conclusion is that the interplay of nematic and SC orders has visible signatures in the thermal transport, which can be used to infer SC gap structure in the coexistence phase.