Anomalous Hall Effect in Topological Antiferromagnetic State in Mn₃Sn

Anomalous Hall effect (AHE), a Hall signal occurring even in absence of external magnetic field, is one of the most attractive phenomena in fundamental science. However, the understanding of its mechanism is challenging and is largely restricted to the ferromagnetic transition metals. Here, we investigate an anomalous thermal Hall effect (ATHE), a thermal analogue of AHE, in the chiral antiferromagnet Mn₃Sn [1]. We find that the amplitude of ATHE scales to the anomalous Hall conductivity according to the Wiedemann-Franz law over a wide temperature range, demonstrating that the AHE of Mn₃Sn arises from a dissipationless intrinsic mechanism induced by the Berry flux. The dissipationless nature of AHE in Mn₃Sn is significantly stabilized by extra Mn atoms which shift the Fermi level toward possible Weyl points and act as a scattering. This result is in sharp contrast to conventional ferromagnetic metals where a doping effect converts the scattering-free AHE into scattering-dependent one. Our findings suggest that the Berry flux in a magnetic Weyl fermion state proposed by ab initio calculations may play an important role for inducing the AHE of Mn₃Sn. [1] S. Nakatsuji, N. Kiyohara, and T. Higo, Nature 527, 212 (2015).