近日，美国麻省理工学院的Joseph G. Checkelsky&Takashi Kurumaji及其研究团队取得一项新进展。经过不懈努力，他们揭示伊辛反铁磁体ErGa₂中的超磁多带霍尔效应。相关研究成果已于2024年5月28日在国际知名学术期刊《美国科学院院刊》上发表。

该研究团队观测到偏磁诱导的单晶ErGa₂的霍尔反常现象，这让人想起了由拓扑霍尔效应引起的特征，但其中Er矩的强伊辛型各向异性阻止了非共面自旋结构。研究人员发现，观测到的反常既不是由于反常霍尔效应，也不是由于拓扑霍尔效应; 相反，可以通过4f-5d相互作用来解释，这种相互作用产生带相关的迁移率调制。这

种相互作用在磁化过程中产生了显著的多带霍尔响应，类似于拓扑霍尔效应的超磁多带霍尔效应，但具有不同的物理起源。当前发现可能在流动的超磁系统中具有普遍意义，不论自旋的共面或非共面性质，对于准确区分由涌现磁场引起的霍尔信号至关重要。

据悉，阻挫稀土基金属间化合物通过导电电子与局域稀土磁矩之间的交换耦合，为涌现磁输运特性提供了一个有前途的平台。超磁性是外加磁场作用下磁化强度的突变，是一阶磁相变的标志。最近，稀土金属间化合物的超磁性转变因其伴随的非寻常自旋结构(如斯格明子)，和相关的非线性和拓扑霍尔效应(THE)而引起了人们的兴趣。

附：英文原文

Title: Metamagnetic multiband Hall effect in Ising antiferromagnet ErGa₂

Author: Kurumaji, Takashi, Fang, Shiang, Ye, Linda, Kitou, Shunsuke, Checkelsky, Joseph G.

Issue&Volume: 2024-5-28

Abstract: Frustrated rare-earth-based intermetallics provide a promising platform for emergent magnetotransport properties through exchange coupling between conduction electrons and localized rare-earth magnetic moments. Metamagnetism, the abrupt change of magnetization under an external magnetic field, is a signature of first-order magnetic phase transitions; recently, metamagnetic transitions in frustrated rare earth intermetallics have attracted interest for their accompanying nontrivial spin structures (e.g., skyrmions) and associated nonlinear and topological Hall effects (THE). Here, we present metamagnetism-induced Hall anomalies in single-crystalline ErGa₂, which recalls features arising from the THE but wherein the strong Ising-type anisotropy of Er moments prohibits noncoplanar spin structures. We show that the observed anomalies are neither due to anomalous Hall effect nor THE; instead, can be accounted for via 4f-5d interactions which produce a band-dependent mobility modulation. This leads to a pronounced multiband Hall response across the magnetization process–a metamagnetic multiband Hall effect that resembles a topological-Hall-like response but without nontrivial origins. The present findings may be of general relevance in itinerant metamagnetic systems regardless of coplanar/noncoplanar nature of spins and are important for the accurate identification of Hall signals due to emergent magnetic fields.

DOI: 10.1073/pnas.2318411121

Source: https://www.pnas.org/doi/abs/10.1073/pnas.2318411121