Anomalous Hall effect in an antiferromagnetic Weyl semimetal

Large intrinsic anomalous Hall effect (AHE) has been considered evidence for Weyl nodes in magnetic Weyl semimetals. Compared to a normal ferromagnet, the AHE in Weyl semimetals originates from an effective field generated by the Weyl nodes, does not require a net magnetization, and should also persist in both the antiferromagnetic (AFM) and paramagnetic (PM) materials. So far, AHE has only been observed in a few AFM Weyl semimetals in magnetic field, including GdPtBi and Mn₃Sn [1,2]. Two different AHE mechanisms have been proposed in these compounds [1,3], posing a general question: what are the AHE mechanisms for other AFM Weyl semimetals?



Here we focus on another Weyl semimetal of the LaPtSi type, and we report the observation of large anomalous Hall conductivity (AHC) (~10² Ohm^-1 cm^-1). In this compound, the AHC increases monotonically on cooling and persists in both the AFM and the PM state up to 100 K. Analysis of our angle-dependent quantum oscillation measurements shows strong evidence of the Weyl pockets close to the Fermi energy in both the AFM and the PM state. Combined with the good conductivity (~10⁴ Ohm^-1 cm^-1), this points to an intrinsic origin of the AHE. We propose a picture for the evolution of the Weyl node under a magnetic field to qualitatively explain the temperature dependence of AHC in our compound.



[1] Shekar, C., et al. PNAS. 115,37 9140-9144. (2018)

[2] Nakatsuji, S., et al. Nature. 527, 212-215. (2016)

[3] Chen, H., et al. Phys. Rev. Lett. 112,017205. (2014)