Thermal transport properties of S = 1/2 Cd-kapellasite

In recent years the thermal Hall effect has gained a great interest as an important signature of the topology. This effect has been observed in paramagnetic phase of kagome antiferromagnets, volborthite and Ca-kapellasite [1]. These thermal Hall conductivities (κ_xy) are shown to be well reproduced by Schwinger-boson mean field theory by tuning the Dzyaloshinskii-Moriya interaction D and the exchange energy J as fitting parameters. In this talk, we report further evidence supporting the agreement between the experiment and theory from thermal Hall measurements in Cd-kapellasite CdCu₃(OH)₆(NO₃)₂ H₂O which has a smaller J/k_B ~ 45 K than that of Ca-kapellasite. We find not only that κ_xy of Cd-kapellasite is also well reproduced by the theory, but also that the peak temperature in κ_xy is shifted to a lower temperature with a larger value in κ_xy as expected by the theory. The good scaling of these kagome materials strongly indicates that a kagome antiferromagnet has a common thermal Hall effect of the kagome spins. [1]H. Doki, M. Akazawa, H. Y. Lee et al., Phys. Rev. Lett. 121, 097203 (2018).