Thermal-transport properties of chiral antiferromagnet CsCuCl₃

Recently, topological effects related to a Berry curvature dipole has been extensively studied in metals without inversion symmetry. On the other hand, these topological effects on charge-neutral bosonic excitations have yet to be clarified. To investigate this issue, we measured the longitudinal and transverse thermal conductivity of the chiral antiferromagnet CsCuCl_3, a high-quality homochiral single crystal of which becomes available very recently. We find a large enhancement of the longitudinal thermal conductivity in the ordered phase. This result suggests a large spin thermal conduction that could not be observed clearly in multi-domain crystals. We further find a sizable thermal Hall effect with a non-linear heater dependence even at zero magnetic field. We will discuss a possible origin for this non-linear thermal Hall effect.