Spin liquid fingerprints in the thermal transport of a Kitaev-Heisenberg ladder

TL;DR

This paper investigates how thermal transport properties in a Kitaev-Heisenberg ladder reveal signatures of quantum spin-liquid behavior, using exact methods to identify energy-dependent transport features and the effects of Heisenberg couplings.

Contribution

It introduces a minimal model analysis showing how finite-temperature thermal transport can detect quantum spin-liquid fingerprints in a Kitaev-Heisenberg ladder.

Findings

Identification of an insulator-conductor crossover at small Heisenberg couplings.

Detection of fracton signatures at various energy scales.

Observation of non-monotonous heat current lifetime dependence on Heisenberg interactions.

Abstract

We identify fingerprints of a proximate quantum spin-liquid (QSL), observable by finite-temperature dynamical thermal transport within a minimal version of the idealized Kitaev model on a two-leg ladder, if subjected to inevitably present Heisenberg couplings. Using exact diagonalization and quantum typicality, we uncover (i) an insulator-conductor crossover induced by fracton recombination at infinitesimal Heisenberg coupling, (ii) low- and high-energy signatures of fractons, which survive far off the pure QSL point, and (iii) a non-monotonous current life-time versus Heisenberg couplings. Guided by perturbation theory, we find (iv) a Kitaev-exchange induced `one-magnon' contribution to the dynamical heat transport in the strong Heisenberg rung limit.