Thermoelectric transport anomaly driven by Berry curvature dipole in (Pb_1-xSn_x)_1-yIn_yTe

Weyl semimetals (WSMs) exhibit chiral anomaly arising from the non-conservation of chiral charge during transport phenomena. The known anomalies require an external magnetic field B parallel to the direction of the Weyl points: when an electric field is applied parallel to B, the ABJ anomaly creates a negative magnetoresistance; when a temperature gradient is applied parallel to B, the gravitational anomaly creates an additional contribution to the thermal conductivity. Here we present experimental evidence for a new type of transport anomaly that arises in the absence of any magnetic field due to the Berry curvature dipole, realized in the WSM phase of (Pb_1-xSn_x)_1-yIn_yTe single crystals. These crystals have been demonstrated to host giant Berry curvature dipoles in the WSM phase, giving rise to a nonlinear Hall effect without the presence of magnetic field or magnetization¹. We show that the Berry curvature dipole also causes the thermal conductivity to exhibit anomalous changes as a function of an external electric field E, with the magnitude of the change proportional to E. In (Pb_0.59Sn_0.41)_0.97In_0.03Te, we observed a linear relationship between imposed electric field along the polar axis and the antisymmetric components of thermal conductivity in the plane normal to z. The antisymmetrized thermal conductivity can be as high as 6.0 x 10^-3 W m⁻¹ K⁻¹ at 305 K and 200 V m^-1. Results were also consistent at low temperatures, with a reported maximum of 2.0 x 10^-3 W m⁻¹ K⁻¹ at 55 K and 200 V m^-1. The observed dependence of thermal conductivity on E-field are in agreement with theoretical predictions.

¹C.-L. Zhang, T. Liang, Y. Kaneko, N. Nagaosa and Y. Tokura, Giant Berry curvature dipole density in a ferroelectric Weyl semimetal, Npj Quantum Mater, 2022, 7, 103.