Spin Thermal Hall Conductivity of a Kagome Antiferromagnet

A clear thermal Hall signal (κxy) was observed in the spin-liquid phase of the S=1/2 kagome antiferromagnet Ca kapellasite [CaCu3(OH)6Cl2·0.6H2O]. We found that κxy is well reproduced, both qualitatively and quantitatively, using the Schwinger-boson mean-field theory with the Dzyaloshinskii-Moriya interaction of D/J∼0.1. In particular, κxy values of Ca kapellasite and those of another kagome antiferromagnet, volborthite, converge to one single curve in simulations modeled using Schwinger bosons, indicating a common temperature dependence of κxy for the spins of a kagome antiferromagnet.