We show that bilayer graphene in the presence of a 2D superlattice potential provides a highly tunable setup that can realize a variety of flat band phenomena. We focus on two regimes: (i) topological flat bands with non-zero Chern numbers, C, including bands with higher Chern numbers |C| > 1; and (ii) an unprecedented phase consisting of a stack of nearly perfect flat bands with C = 0. For realistic values of the potential and superlattice periodicity, this stack can span nearly 100 meV, encompassing nearly all of the low-energy spectrum. We further show that in the topological regime, the topological flat band has a favorable band geometry for realizing a fractional Chern insulator (FCI) and use exact diagonalization to show that the FCI is in fact the ground state at 1/3 filling. Our results provide a realistic guide for future experiments to realize a new platform for flat band phenomena.
@article{arxiv.2206.13501,
title = {Topological and stacked flat bands in bilayer graphene with a superlattice potential},
author = {Sayed Ali Akbar Ghorashi and Aaron Dunbrack and Ahmed Abouelkomsan and Jiacheng Sun and Xu Du and Jennifer Cano},
journal= {arXiv preprint arXiv:2206.13501},
year = {2023}
}
Comments
14 pages including supplementary materials. Published version