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

Abstract

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.