May 19, 2022
News & Views: Spin-liquid evidence at the edge and in the bulk of RuCl3
Hopes for a topological spin-liquid phase in ruthenium trichloride have been previously raised by evidence of Majorana modes at the material’s edges. Thermal Hall effect and specific heat measurements now strengthen the case for Majorana fermions.
Early thermal Hall effect data for the Kitaev material RuCl3 which seem to support topologically protected Majorana fermion edge currents with a gapped bulk state have now been corroborated by new measurements by Bruin et al. [1]. Further support by Tanaka et al. [2] is generated by bulk-sensitive magnetic-field direction-dependent specific-heat data, which imply a field-angle dependence of the bulk gap which is in line with theoretical expectations for the topological state in the Kitaev model.
The new findings underpin the intriguing plethora of new physics which comes along with potential topological properties in frustrated quantum materials. However, despite the compelling new findings many questions remain to be settled such as the relevance of non-Kitaev couplings as well as thermal Hall effect contributions from phonons, magnons or visons.
[1] J. A. N. Bruin et al., Nat. Phys. 18, 401 (2022).
[2] O. Tanaka et al., Nat. Phys. 18, 429 (2022).
A. U. B. Wolter and C. Hess,
Spin liquid evidence at the edge and in bulk,
Nat. Phys. (2022)