Spin Thermal Hall Conductivity of a Kagomé Antiferromagnet

Abstract

A clear thermal Hall signal (${\kappa }_{xy}$) was observed in the spin liquid phase of the $S=1/2$ kagomé antiferromagnet Ca kapellasite (CaCu${}_3$(OH)${}_6$Cl${}_2\cdot 0.6$H${}_2$O). We found that ${\kappa }_{xy}$ is well reproduced, both qualitatively and quantitatively, using the Schwinger-boson mean-field theory with the Dzyaloshinskii--Moriya interaction of $D/J\sim 0.1$. In particular, ${\kappa }_{xy}$ values of Ca kapellasite and those of another kagomé antiferromagnet, volborthite, converge to one single curve in simulations modeled using Schwinger bosons, indicating a common temperature dependence of ${\kappa }_{xy}$ for the spins of a kagomé antiferromagnet.

5 pages, 4 figures + Supplemental Material(9 pages, 6 figures)