Quantum anomalous Hall effect in an antiferromagnetic monolayer of MoO

Abstract

The quantum anomalous Hall (QAH) effect is rarely predicted in antiferromagnetic (AFM) materials. Here, by first-principles calculations, we propose that the monolayer of MoO is AFM and can be tuned to be a QAH insulator with a band gap of 50 meV. The MoO monolayer is a tetragonal lattice and we have checked its stability by the phonon spectrum and molecular dynamical simulation. It has a collinear AFM order with magnetic moments larger than $2\phantom{\rule{0.16em}{0ex}}{\ensuremath{\mu}}_{B}$ on each Mo atom. In the absence of strain, it is an AFM metal with a direct gap if spin-orbital coupling is considered. Tensile strain results in a metal-insulator phase transition, but it is still topologically trivial protected by an effective time-reversal symmetry. Shear strain breaks this symmetry and leads to the expected nontrivial electronic bands with Chern number $C=\ensuremath{-}1$. In addition, its N\'eel temperature could be larger than room temperature, providing another platform for the application of AFM materials in spintronic devices.