Flat Chern Band from Twisted Bilayer MnBi_{2}Te_{4}

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Phenomena

Background:

• Topological materials offer unique electronic properties.
• Moiré superlattices in twisted 2D materials create novel electronic band structures.
• MnBi2Te4 is a promising material for exploring topological and magnetic phenomena.

Purpose of the Study:

• To model the moiré superlattice of twisted bilayer MnBi2Te4.
• To investigate the band structure in ferromagnetic (FM) and antiferromagnetic (AFM) phases.
• To explore the potential for realizing correlated topological phases and quantum anomalous Hall effect.

Main Methods:

• Construction of a continuum model for twisted bilayer MnBi2Te4.
• Band structure calculations for FM and AFM phases.
• Analysis of Chern bands and their properties.

Main Results:

• The system exhibits highly tunable Chern bands with Chern numbers up to 3.
• A twist angle of 1° results in an isolated flat band with Chern number ±1 in both FM and AFM phases.
• Twisted stacking facilitates the emergence of the quantum anomalous Hall effect.

Conclusions:

• Twisted bilayer MnBi2Te4 is a promising platform for realizing time-reversal breaking correlated topological phases.
• The identified flat bands are ideal for hosting fractional Chern insulator and p+ip topological superconductor states.
• This work highlights the potential of moiré engineering in MnBi2Te4 for novel quantum phenomena.