Heat transport in the anisotropic Kitaev spin liquid

TL;DR

This paper investigates heat transport in the anisotropic Kitaev spin liquid, revealing normal dissipative thermal conductivity in both gapless and gapped phases through large-scale numerical simulations.

Contribution

It combines exact diagonalization and gauge configuration averaging to analyze thermal transport across different phases of the anisotropic Kitaev model, covering large system sizes.

Findings

Both phases exhibit normal dissipative transport in the thermodynamic limit.

Thermal conductivity shows a crossover from power-law to exponential behavior with gap opening.

Emergent gauge disorder influences current correlations but not the overall transport nature.

Abstract

We present a study of longitudinal thermal transport in the Kitaev spin model on the honeycomb lattice, focusing on the role of anisotropic exchange to cover both, gapless and gapped phases. Employing a complementary combination of exact diagonalization on small systems and an average gauge configuration approach for up to $\sim O(10^4)$ spinful sites, we report results for the dynamical energy current auto-correlation function as well as the dc thermal conductivity over a wide range of temperatures and exchange anisotropies. Despite a pseudogap in the current correlation spectra, induced by emergent thermal gauge disorder on any finite system, we find that in the thermodynamic limit, gapless and gapful phases both feature normal dissipative transport, with a temperature dependence crossing over from power law to exponentially activated behavior upon gap opening.