Intrinsic Origin Investigation of AHE and Thermoelectric in Weyl Semimetal Mn3Ge

摘要: Intrinsic (Berry curvature) origin of the anomalous Hall effect (AHE) once had been a controversy for decades in ferromagnetic systems. Since there are three mechanisms account for the AHE: skew-scattering, side-jump and Berry curvature, which dominates in the super clean and good magnetic metals, respectively [1]. Especially, in ferromagnets it is very difficult to differentiate the AHE contributions between side-jump and Berry curvature mechanism, because they have the same longitudinal resistivity dependence, 𝜌𝐴𝐻∝ 𝜌2𝑀, where 𝜌 and M are longitudinal resistivity and magnetization. Recently, the observation of the AHE in antiferromagnets has been reported for the inverse triangle spin texture Mn3Sn [2-4] and Mn3Ge [5, 6]. Different from the ferromagnets, this coplanar but noncollinear spin structure does not induce magnetization or very tiny of about a few mµB/Mn with inplane directions, which offer a very ideal platform for the investigation on intrinsic (Berry Curvature) origin. Here, we show our recent work on the study of the AHE of Mn3Ge. Single crystals of Mn3Ge with size of about 1 cm length have been grown. Systematic transport measurement results show that the temperature cooling resistivity along [0001] and [2-1-10] directions has typical metallic behavior with the residual resistivity ratio (RRR) about 3. Interestingly, with increasing temperature from 2K to 200K the Hall resistivity can also be several times larger, while the magnetization changes very tiny, indicating the failure of the conventional AHE formula, and requires the Berry curvature description. Besides, Nernst signal was found to be rather large and evolve with …