Strain-engineering quantum anomalous hall state in janus MnBi2SexTe4−x monolayers

Abstract

Exploring intrinsic magnetic topological insulators (TIs) for next-generation spintronic devices is still challenging in recent years. Here, we present a theoretical investigation on the electronic, magnetic and topological properties of monolayer (ML) Janus MnBi₂Se_xTe_4−x (1 ≤ x ≤ 3), derived from two trivial magnetic semiconductors ML MnBi₂Se₄ and MnBi₂Te₄. Our band structure analysis reveals that two out of the six Janus structures exhibit band inversion induced by spin–orbit coupling. These structures are confirmed to have nonzero integer Chern numbers, indicating their topological nature. Moreover, the topological state is robust under moderate biaxial strains. Interestingly, applying compressive strain results in a high Chern number of 2 and enhances their magnetic stability at elevated temperatures. Our findings offer an effective strategy to engineer magnetic TI states within the ML MnBi₂Te₄ family.