The magnetic properties, flat and Dirac bands of two-dimensional room-temperature ferromagnetic Kagome material Mn3Sn3Se2

The Kagome lattice is rich in unique electronic and magnetic properties, such as flat band, superconductivity, charge density waves, and so on. In this paper, the magnetic properties, flat and Dirac bands of monolayer Mn₃Sn₃Se₂ with Kagome lattice are investigated based on first-principles calculations. A total of four magnetic configurations are considered, and the intrinsic ground state of Mn₃Sn₃Se₂ is identified as the ferromagnetic state. Strain has a significant effect on its magnetic ground state, which changes to an in-plane AFM state when the tensile strain exceeds 5 %. Monolayer Mn₃Sn₃Se₂ has an out-of-plane magnetic anisotropy of up to 0.777 meV, and the Curie temperature is 528 K. The band structure of the FM state is shown to be metallic, and spin polarized flat and Dirac bands appear near the Fermi level, which are degenerate. Monolayer Mn₃Sn₃Se₂ changes to half-metallic when a strain of 1%–2% is applied. Strain and correlation effects can significantly alter the flatness of flat band and the relative energy with Dirac bands. These results not only enrich the family of two-dimensional ferromagnets, but also provide a reference for studying the regulation of flat and Dirac bands.