Magnetic Excitations across Topological Phase Transition in the Weyl Semimetal Mn3Sn

Mn3Sn is a magnetic Weyl semimetal exhibiting a large anomalous Hall effect without net magnetization at room temperature, opening the possibility for spintronic memory without stray fields. These fascinating properties emerge from the nonzero Berry curvature in the inverse triangular antiferromagnetic structure on the Kagome lattice of Mn atoms. The nonzero Berry curvature is attributed to the existence of local cluster multipole moments, a generalization of the uniform magnetization in ferromagnets. This notion has been supported by the disappearance of terahertz anomalous Hall effect upon entering the helical magnetic state. We aim to understand the evolution of collective spin excitations across the topological phase transition, by utilizing high-resolution soft-x-ray RIXS at the Mn L3 edge.

Mn3Sn是一种在室温下无需净磁化强度即可呈现大反常霍尔效应的磁性外尔半金属（magnetic Weyl semimetal），为无杂散场的自旋电子学存储器研发开辟了新路径。这类引人瞩目的物性源于锰原子Kagome晶格（Kagome lattice）上反三角反铁磁结构所产生的非零贝里曲率（Berry curvature）。非零贝里曲率可归因于局域团簇多极矩的存在——这是铁磁体中均匀磁化强度概念的推广。该观点已通过螺旋磁态下太赫兹反常霍尔效应消失的实验结果得到验证。本研究旨在借助锰L₃边处的高分辨软X射线共振非弹性X射线散射（resonant inelastic X-ray scattering, RIXS），解析拓扑相变过程中集体自旋激发的演化规律。