Magnetic excitations and electronic structure of Kagome metal FeGe

Two-dimensional (2D) layered Kagome compounds are great platforms to study not only magnetic frustration but also topological phases that realize flat bands. It is predicted that the Kagome lattice can be constructed to realize flat band physics at 1/3 filling and quantum anomalous Hall effect mainly at 2/3 filling. Recently, a family of Kagome metals T_mX_n (T: Fe, Co, X: Sn,Ge, m:n = 3:1, 3:2, 1:1) has attracted much interests. Although flat bands and Dirac crossings are expected in the single-orbital nearest-neighbor Kagome model, possible complications from evolution of the magnetic order and strong electron-electron interactions remain largely unexplored experimentally. Here I will present a new Kagome system - FeGe. Distinct from widely studied planar antiferromagnetic (AFM) FeSn (T_N = 365 K) and paramagnetic CoSn, it has a collinear c-axis antiferromagnetic (AFM) structure between T­­_N = 410 K and T₁ ~ 60 K, followed by an AFM spiral structure below T₁ ~ 60 K.

In this talk, I will focus on systematic studies of the magnetic excitations and electronic structures via neutron scattering and angle-resolved photoemission spectroscopy measurements, which reveal this system to be an exciting new platform for studying correlation and magnetism in the presence of topology.