Alkali metal-doped two-dimensional Janus Cr₂Br₃I₃ monolayers with the quantum anomalous Hall effect

The quantum anomalous Hall effect (QAHE) has great potential in manufacturing low-energy electronic devices. In this study, the electromagnetic and topological properties of the alkali metal (Li/Na/K)-doped Janus Cr2Br3I3 monolayer are systematically investigated using first-principles calculations. It was found that the Li/Na/K-doped Cr2Br3I3 has good stability and presents a ferromagnetic ground state with in-plane magnetic anisotropy. The Li/Na/K-doped Cr2Br3I3 exhibits a half-metallic state with 100% spin polarization, which is different from the semiconductor state for pristine Cr2Br3I3 Interestingly, the Na- and K-doped Cr2Br3I3 display QAHE characteristics with the Chern number of C = 2. Moreover, the half-metallic behavior and QAHE characteristics are not sensitive to the change in effective U values. Our work provides a theoretical guideline for realizing the multichannel QAHE based on two-dimensional ferromagnetic Janus systems.