Topological thermal Hall effect in frustrated kagome antiferromagnets

In frustrated magnets the Dzyaloshinsky-Moriya interaction (DMI) arising from spin-orbit coupling can induce a magnetic long-range order. Here, we report a theoretical prediction of the thermal Hall effect in frustrated kagome magnets such as KCr3(OH)6(SO4)2 and KFe3(OH)6(SO4)2. The thermal Hall effects in these materials are induced by scalar spin chirality as opposed to DMI in previous studies. The scalar spin chirality originates from the magnetic-field-induced chiral spin configuration due to noncoplanar spin textures, but in general it can be spontaneously developed as a macroscopic order parameter in chiral quantum spin liquids. Therefore, we infer that there is a possibility of the thermal Hall effect in frustrated kagome magnets such as herbertsmithite ZnCu3(OH)6Cl2 and the chromium compound Ca10Cr7O28, although they also show evidence of magnetic long-range order in the presence of applied magnetic field or pressure.