Quantum anomalous Hall state in a fluorinated 1T−MoSe2 monolayer

The quantum anomalous Hall state with a large band gap and a high Chern number is significant for practical applications in spintronics. By performing first-principles calculations, we investigate electronic properties of the fully fluorinated $1T\text{\ensuremath{-}}{\mathrm{MoSe}}_{2}$ monolayer. Without considering the spin-orbit coupling, the band structure demonstrates single-spin semimetallic properties and the trigonal warping around ${K}_{\ifmmode\pm\else\textpm\fi{}}$ valleys. The introduction of the spin-orbit coupling opens considerable band gaps of 117.2 meV around the two valleys, leading to a nontrivial quantum anomalous Hall state with a Chern number of $|C|=2$, which provides two chiral dissipationless transport channels from topological edge states and associated quantized anomalous Hall conductivity. In addition, an effective model is constructed to describe the low-energy physics of the monolayer. Our findings in the ${\mathrm{MoSe}}_{2}{\mathrm{F}}_{2}$ monolayer shed light on large-gap quantum anomalous Hall states in two-dimensional materials with the chemical functionalization, and provide opportunities to design low-power and noise-tolerant spintronic devices.