Unconventional anomalous Hall effect and large anomalous Nernst effect in antiferromagnet SmMnBi₂

The anomalous Hall effect (AHE) and anomalous Nernst effect (ANE) are transverse transport coefficients typically linked to ferromagnetism, yet recent work shows they can arise in nonmagnetic and antiferromagnetic topological materials. Here we report an unconventional AHE (UAHE) that does not scale with magnetization and a sizable ANE (≈1.8 μV K−1) in the metallic tetragonal antiferromagnet SmMnBi₂. Angle-resolved photoemission spectroscopy (ARPES) and first-principles calculations probe the electronic band structure. We demonstrate that the UAHE reflects an intrinsic Berry-curvature contribution stemming from spin-canted antiferromagnetism, whereas the ANE is likely further amplified by extrinsic mechanisms. SmMnBi₂ thus emerges as a promising platform for exploring unusual transverse transport effects and their rich underlying physics.

Kaixin Tang, Ye Yang, Jianchang Shen, Mengzhu Shi, Nan Zhang, Houpu Li, Hongyu Li, Zhengtai Liu, Dawei Shen, Rui Wang, Yang Gao, Junfeng He, Ziji Xiang, Xianhui Chen