Magnon-polaron driven thermal Hall effect in a Heisenberg-Kitaev antiferromagnet

Abstract

The thermal Hall effect, where a transverse heat current is generated in response to a longitudinal temperature gradient, probes charge-neutral excitations in insulating quantum matter. By studying thermal transport in the Heisenberg-Kitaev antiferromagnet and spin liquid candidate Na${}_{2}$Co${}_{2}$TeO${}_{6}$, the authors find here that magnon polarons, i.e., hybridized phonons and magnons produced by spin-lattice coupling, govern the sign and magnitude of the observed signal. This is in contrast to a pure magnon transport theory, which fails to capture important features of the experiment.