Intrinsic Anomalous Nernst Effect Amplified by Disorder in a Half-Metallic Semimetal

Abstract

Intrinsic anomalous Nernst effect, like its Hall counterpart, is generated by Berry curvature of electrons in solids. Little is known about its response to disorder. In contrast, the link between the amplitude of the ordinary Nernst coefficient and the mean-free path is extensively documented. Here, by studying Co3Sn2S2, a topological half-metallic semimetal hosting sizable and recognizable ordinary and anomalous Nernst responses, we demonstrate an anticorrelation between the amplitudes of carrier mobility and the anomalous SxyA (the ratio of transverse electric field to the longitudinal temperature gradient in the absence of magnetic field). We argue that the observation, paradoxically, establishes the intrinsic origin of the anomalous Nernst effect in this system. We conclude that various intrinsic off-diagonal coefficients are set by the way the Berry curvature is averaged on a grid involving the mean-free path, the Fermi wavelength, and the de Broglie thermal length.