Intrinsic 2D ferromagnetism, quantum anomalous Hall conductivity, and fully-spin-polarized edge states of FeBr3 monolayer

It is of great interest to explore intrinsic two-dimensional ferromagnetism and seek better two-dimensional quantum anomalous Hall insulator materials. Here, we show that the FeBr$_3$ monolayer is an intrinsic two-dimensional ferromagnetic material whose Curie temperature is 140 K thanks to its strong spin exchange interaction and giant uniaxial magnetic anisotropy. Our phonon spectra and mechanical analysis indicate that the FeBr$_3$ monolayer is dynamically and mechanically stable. Our electronic structure calculation shows that there is one Dirac cone at K point in the Brillouin zone and the spin-orbit coupling opens a semiconductor gap of 33.5 meV. Further tight-binding analysis reveals that the Chern number is equivalent to 1 and there is a quantum anomalous Hall conductivity $\sigma _{xy} = e^2/h$, and the chiral edge states are fully spin-polarized when an edge is created. Furthermore, it is shown that the main results are not affected by electron correlation effects and biaxial strain. Therefore, this FeBr$_3$ monolayer as 2D material would be useful for spintronic applications.