Strain-engineering quantum anomalous Hall effect in janus MnBi2SexTe4-x monolayers

TL;DR

This study theoretically demonstrates how strain can induce and enhance quantum anomalous Hall effects in Janus MnBi2SexTe4-x monolayers, revealing new pathways for spintronic device applications.

Contribution

It introduces a novel strain-engineering approach to realize and control topological magnetic states in Janus MnBi2Te4-based monolayers.

Findings

Two Janus structures exhibit band inversion and nonzero Chern numbers.

Moderate biaxial strain preserves topological states.

Compressive strain increases Chern number to 2 and improves magnetic stability.

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 MnBi2TexSe4-x, derived from two trivial magnetic semiconductors ML MnBi2Se4 and MnBi2Te4. Our band structure analysis reveals that two out of the eight 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.