Angular-Dependent Thermal Hall Effect in a Honeycomb Magnet: Disentangling Kitaev and Dzyaloshinskii-Moriya Interactions

TL;DR

This study uses angular-dependent thermal Hall measurements on a honeycomb magnet to distinguish between Kitaev and Dzyaloshinskii-Moriya interactions, revealing DMI as the primary cause of the observed thermal Hall effect.

Contribution

It demonstrates that angular-dependent thermal Hall measurements can effectively differentiate between Kitaev and Dzyaloshinskii-Moriya interactions in quantum magnets.

Findings

Thermal Hall response persists for both out-of-plane and in-plane magnetic fields.

The response is governed by the projection between magnetic moments and a tilted DMI vector.

DMI-driven topological magnetic excitations are identified as the origin of the thermal Hall effect.

Abstract

Layered honeycomb magnets have garnered significant attention recently for their exotic quantum phenomena due to the potential anisotropic, bond-dependent Kitaev interactions. However, distinguishing the roles of Kitaev interactions and the symmetry-allowed Dzyaloshinskii-Moriya interaction (DMI) remains challenging, since both mechanisms may lead to similar magnetic excitations and thermal transport properties. To tackle this challenge, using a ferromagnetic honeycomb insulator VI3 as a model system, we systematically study the angular-dependent thermal Hall conductivity Kxy({\theta}, {\Phi}) with both out-of-plane ({\theta}) and in-plane ({\Phi}) magnetic field rotations. Our results reveal a persistent thermal Hall response for both out-of-plane and in-plane rotating magnetic fields, devoid of the sign-reversal patterns characteristic of Kitaev physics. Instead, quantitative analysis shows that the angular dependent Kxy({\theta}, {\Phi}) is governed by the projection between the magnetic moment and a tilted DM vector containing both out-of-plane and in-plane components. These results not only establish the DMI-driven topological magnetic excitations as the origin of the thermal Hall response in VI3 but also highlight the angular-dependent thermal Hall effect measurements as an effective approach for distinguishing competing interactions in quantum magnets.