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Two-dimensional (2D) topological insulators, characterized by dissipationless edge states, are a pivotal platform for studying the interplay between magnetism and topology. Key manifestations of this interplay include the quantum spin Hall effect and the quantum anomalous Hall effect. This study investigates the bilayer structures of a novel 2D magnetic topological material, T-RuO2. Our findings reveal that the ferromagnetic states observed in the T-RuO2 bilayer with AA- or AB-stacking give rise to a quantum anomalous Hall state characterized by a high Chern number (C = −4) with a band gap of 137 meV (AA stacking) and 139 meV (AB stacking). In contrast, the antiferromagnetic bilayer is identified as a quantum spin Hall insulator, indicated by a nontrivial invariant Z2. Furthermore, we explore the influence of an out-of-plane external electric field on tuning the electronic and topological properties. By effectively tuning the band gap, the electric field may cause a transition from a topological insulating state to a traditional metallic state, which indicates its potential application in topological electronics. These results underscore the significant tunability of the T-RuO2 bilayer system, providing a theoretical foundation for the design of magnetic topological materials and their potential applications in quantum devices.
Wang et al. (Thu,) studied this question.