Renormalization of thermal conductivity of disordered d-wave superconductors by impurity-induced local moments

TL;DR

This paper investigates how impurity-induced local magnetic moments can significantly suppress the universal low-temperature thermal conductivity in disordered d-wave superconductors, challenging previous assumptions of its independence from disorder.

Contribution

It introduces a model incorporating electronic correlations and impurity effects, revealing the impact of local moments on thermal conductivity renormalization in disordered superconductors.

Findings

Local magnetic moments around impurities enhance localization effects.

Suppression of thermal conductivity can be much stronger than previously expected.

Impurity-induced moments break the universality of low-temperature thermal transport.

Abstract

The low-temperature thermal conductivity \kappa_0/T of d-wave superconductors is generally thought to attain a "universal" value independent of disorder at sufficiently low temperatures, providing an important measure of the magnitude of the gap slope near its nodes. We discuss situations in which this inference can break down because of competing order, and quasiparticle localization. Specifically, we study an inhomogeneous BCS mean field model with electronic correlations included via a Hartree approximation for the Hubbard interaction, and show that the suppression of \kappa_0/T by localization effects can be strongly enhanced by magnetic moment formation around potential scatterers.