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.