Experimental Evidence for a Berry Curvature Quadrupole in an Antiferromagnet

作者：Soumya Sankar, Ruizi Liu, Cheng-Ping Zhang, Qifang Li, Caiyun Chen, Xue-Jian Gao, Jiangchang Zheng, Yi‐Hsin Lin, Kun Qian, Ruo-Peng Yu, Xu Zhang, Zi Yang Meng, K. T. Law, Qiming Shao, Berthold Jäck · 发表于：Physical Review X · 年份：2024 · DOI：10.1103/physrevx.14.021046 · 被引用次数：36 · 研究领域：Topological Materials and Phenomena、Magnetic properties of thin films、Physics of Superconductivity and Magnetism

Berry curvature multipoles appearing in topological quantum materials have recently attracted much attention. Their presence can manifest in novel phenomena, such as nonlinear anomalous Hall effects (NLAHE). The notion of Berry curvature multipoles extends our understanding of Berry curvature effects on the material properties. Hence, research on this subject is of fundamental importance and may also enable future applications in energy harvesting and high-frequency technology. It was shown that a Berry curvature dipole can give rise to a second-order NLAHE in materials of low crystalline symmetry. Here, we demonstrate a fundamentally new mechanism for Berry curvature multipoles in antiferromagnets that are supported by the underlying magnetic symmetries. Carrying out electric transport measurements on the kagome antiferromagnet FeSn, we observe a third-order NLAHE, which appears as a transverse voltage response at the third harmonic frequency when a longitudinal ac drive is applied. Interestingly, this NLAHE is strongest at and above room temperature. We combine these measurements with a scaling law analysis, a symmetry analysis, model calculations, first-principle calculations, and magnetic Monte Carlo simulations to show that the observed NLAHE is induced by a Berry curvature quadrupole appearing in the spin-canted state of FeSn. At a practical level, our study establishes NLAHE as a sensitive probe of antiferromagnetic phase transitions in other materials—such as moiré su...