Low Temperature Thermal Hall Conductivity of a Nodal Chiral Superconductor

TL;DR

This paper investigates the thermal Hall conductivity in a nodal chiral superconductor, inspired by Sr2RuO4, revealing conditions under which it can be substantial at low temperatures.

Contribution

It provides a theoretical evaluation of the thermal Hall conductivity in a gapless regime with impurity scattering, highlighting its potential significance.

Findings

Thermal Hall conductivity can be significant in certain conditions.

It is smaller than the universal thermal conductivity by a factor involving the gap and impurity bandwidth.

The study focuses on the low-temperature, impurity-dominated regime.

Abstract

Motivated by Sr2RuO4, we consider a chiral superconductor where the gap is strongly suppressed along certain momentum directions. We evaluate the thermal Hall conductivity in the gapless regime, i.e., at temperature small compared with the impurity band width \gamma, taking the simplest model of isotropic impurity scattering. We find that, under favorable circumstances, this thermal Hall conductivity can be quite significant, and is smaller than the diagonal component (the universal thermal conductivity) only by a factor of 1/ ln(2 \Delta_M/\gamma), where \Delta_M is the maximum gap.