Planar thermal Hall effect of topological bosons in the Kitaev magnet α-RuCl 3

The honeycomb magnet α-RuCl has attracted considerable interest because it is proximate to the Kitaev Hamiltonian whose excitations are Majoranas and vortices. The thermal Hall conductivity κ of Majorana fermions is predicted to be half-quantized. Half-quantization of κ /T (T, temperature) was recen...

Full description

Saved in:
Bibliographic Details
Published in:Nature materials 2023-01, Vol.22 (1), p.36
Main Authors: Czajka, Peter, Gao, Tong, Hirschberger, Max, Lampen-Kelley, Paula, Banerjee, Arnab, Quirk, Nicholas, Mandrus, David G, Nagler, Stephen E, Ong, N P
Format: Article
Language:English
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:The honeycomb magnet α-RuCl has attracted considerable interest because it is proximate to the Kitaev Hamiltonian whose excitations are Majoranas and vortices. The thermal Hall conductivity κ of Majorana fermions is predicted to be half-quantized. Half-quantization of κ /T (T, temperature) was recently reported, but this observation has proven difficult to reproduce. Here, we report detailed measurements of κ on α-RuCl with the magnetic field B ∥ a (zigzag axis). In our experiment, κ /T is observed to be strongly temperature dependent between 0.5 and 10 K. We show that its temperature profile matches the distinct form expected for topological bosonic modes in a Chern-insulator-like model. Our analysis yields magnon band energies in agreement with spectroscopic experiments. At high B, the spin excitations evolve into magnon-like modes with a Chern number of ~1. The bosonic character is incompatible with half-quantization of κ /T.
ISSN:1476-4660