From degenerate flat bands to topological states with high Chern numbers
Phys. Rev. B 111, 235130 – Published 18 June, 2025
DOI: https://doi.org/10.1103/cw6h-dr47
Abstract
Flat-band systems have attracted tremendous attention due to their important role in exotic strongly correlated phenomena, such as superconductivity, magnetism, and fractional Chern insulators recently observed in moiré materials. Here we systematically demonstrate the emergence of degenerate flat bands in different lattice models with simple near-neighbor hopping parameters, including the kagomé lattice, the kagomé-honeycomb lattice and the star lattice. Interestingly, the degeneracy can be lifted by staggered magnetic fluxes, typically leading to a couple of nearly flat topological bands with high Chern numbers . Finally we show the possibility of fractional Chern insulators when interacting electrons partially fill these nearly flat Chern bands.
