First-principles study of Dirac fermions in the ferromagnetic kagome metal Fe₃Sn₂

The kagome lattice, along with the honeycomb lattice, is among the simplest theoretical models anticipated to host Dirac fermions in their tight-binding band structures. In recent years, electronic Dirac fermions have been discovered in a series of transition element-based kagome metals, among which the ferromagnetic Fe₃Sn₂ stands as one of the initial examples. Spectroscopic, transport, and thermodynamic experiments have revealed the presence of quasi-two-dimensional massive Dirac fermions in Fe₃Sn₂ [1,2]. Here we present a comprehensive first-principles study of the electronic structure of Fe₃Sn₂ to clarify the origin of the observed Dirac fermions and the nature of the electronic topology in the system. Our findings suggest that the massless Dirac fermions in the non-relativistic limit in Fe₃Sn₂ are subject to a Kane-Mele type spin-orbit coupling. We will also discuss our study's implications on realizing low-dimensional lattice models using three-dimensional crystalline materials.

[1] L. Ye, M. Kang et al., Nature 555 638-642 (2018).
[2] L. Ye et al., Nat. Commun. 10, 4870 (2019).