Anomalous Nernst and Righi-Leduc Effects in Mn3Sn:Berry Curvature and Entropy Flow*

In addition to the ordinary Hall effect, the transverse electric field generated by a longitudinal charge current in the presence of a magnetic field. In ferromagnetic solids, there is an additional component to the transverse current generated by an electric field in presence of magnetic field. This Anomalous Hall effect (AHE) is a result of the Berry curvature of the Bloch waves. Recently, following theoretical propositions [1], a large AHE has been observes in noncollinear antiferromagnets Mn₃Sn and Mn₃Ge [2-4].
We will present a study of thermoelectric and thermal response in Mn₃Sn beyond electric measurement. We measured Nernst and Righi-Leduc (or thermal hall) effects, and compared their anomalous components to their Hall counterpart. We found that the anomalous Nernst and Hall conductivities are strongly temperature-dependent and their ratio is 15 µV/K at room temperature and peaks to 50µV/K, close to k_B/e(= 86 µV/K) . We found that the thermal and electrical Hall conductivities respect the Wiedemann-Franz law, and in contrast to conventional ferromagnets, the anomalous Lorenz number remains close to the Sommerfeld number over the whole temperature range of study [5].
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5.X. Li, L. Xu, L. Ding, J. Wang, M. Shen, X. Lu, Z. Zhu and K . Behnia, Phys. Rev. Lett. 119, 056601 (2017)