Tunable Topological States in Stacked Chern Insulator Bilayers.

Area of Science:

• Condensed matter physics
• Materials science
• Quantum magnetism

Background:

• Intrinsic quantum anomalous Hall (QAH) insulators with ferromagnetic (FM) order are key for low-dimensional topology and magnetism.
• Atom-thin Chern insulator monolayer MnBr3 serves as a foundation for novel topological structures.

Purpose of the Study:

• To explore tunable topological electronic states in stacked Chern insulator bilayers.
• To investigate the impact of magnetic orders and external fields on topological properties.
• To demonstrate a novel layer Hall effect in antiferromagnetic bilayers.

Main Methods:

• Theoretical modeling of stacked Chern insulator bilayers.
• Analysis of electronic band structures and Berry curvature.
• Simulation of magneto-optical Kerr effect and layer Hall effect.

Main Results:

• Ferromagnetic bilayers exhibit high-Chern-number QAH states with quantized Hall plateaus and specific Kerr angles.
• Antiferromagnetic bilayers show emergent Berry curvature singularities induced by electric/optical fields.
• A novel layer Hall effect, dependent on light chirality, is demonstrated in antiferromagnetic bilayers.

Conclusions:

• Stacked Chern insulator bilayers offer abundant tunable topological properties.
• A universal strategy is proposed for modulating d-orbital-dominated topological Dirac fermions.
• This work opens avenues for designing novel topological quantum devices.