A Generic Designing Rule for Realizing Quantum Anomalous Hall Phase in a Transition-Metal Trichalcogenide Family

Different from introducing ferromagnetism in three-dimensional (3D) topological insulators, empowering nontrivial band topology with 2D ferromagnetic (2DFM) materials is another way to realize quantum anomalous Hall effect (QAHE). The recently discovered 2DFM insulators provide unprecedented opportunities for realizing such an intriguing quantum phenomenon. Here, by using first-principles approaches, we design a generic rule for realizing QAHE in the transition-metal trichalcogenide family materials of Cr2A2X6 (where A = Si, Ge, Sn; X = S, Se, Te), whose design principle is based on that a 2D topologically trivial magnetic insulator can be converted into a QAH system via proper surface modification. Taking silicene-passivated Cr2Sn2Se6 as an illustration, we show that the Cuire temperature of Cr2Sn2Se6 monolayer can be enhanced up to ∼92 K after silicene passivation. Most strikingly, such a heterostructure harbors QAHE with a band gap of ∼30 meV. Further low-effective model analyses reveal that the topologically nontrivial states are attributed to the honeycomb lattice of Cr atoms. All those results demonstrate that our proposal is general, which opens a new avenue to explore high-temperature QAHE.