Tunable Topological States in Stacked Chern Insulator Bilayers

The emergence of intrinsic quantum anomalous Hall (QAH) insulators with a long-range ferromagnetic (FM) order triggers unprecedented prosperity for combining topology and magnetism in low dimensions. Built upon atom-thin Chern insulator monolayer MnBr3, we propose that the topologically nontrivial electronic states can be systematically tuned by inherent magnetic orders and external electric/optical fields in stacked Chern insulator bilayers. The FM bilayer illustrates a high-Chern-number QAH state characterized by both quantized Hall plateaus and specific magneto-optical Kerr angles. In antiferromagnetic bilayers, Berry curvature singularity induced by electrostatic fields or lasers emerges, which further leads to a novel implementation of the layer Hall effect depending on the chirality of irradiated circularly polarized light. These results demonstrate that abundant tunable topological properties can be achieved in stacked Chern insulator bilayers, thereby suggesting a universal routine to modulate d-orbital-dominated topological Dirac fermions.

Automated summary

The emergence of long-range ferromagnetic quantum anomalous Hall (QAH) insulators has opened up new possibilities for combining topology and magnetism in low dimensions. By using atom-thin Chern insulator monolayer MnBr3, the topologically nontrivial electronic states can be systematically tuned by magnetic orders and external fields in stacked Chern insulator bilayers. The bilayers show high-Chern-number QAH states with quantized Hall plateaus and specific magneto-optical Kerr angles in ferromagnetic cases, and Berry curvature singularity induced by electrostatic fields or lasers in antiferromagnetic cases, leading to a novel layer Hall effect depending on the chirality of irradiated circularly polarized light. These findings suggest a universal routine to modulate d-orbital-dominated topological Dirac fermions.