At large commensurate angles, twisted bilayer graphene which holds even parity under sublattice exchange exhibits a tiny gap. Here, we point out a way to tune this tiny gap into a large gap. We start from comprehensive understanding of the physical origin of gap opening by density functional theory calculations. We reveal that the effective inter-layer hopping, intra-layer CDW, or inter-layer charge imbalance favors a gap. Then, on the basis of tight-binding calculations, we suggest that a periodic transverse inhomogeneous pressure, which can tune inter-layer hoppings in specific regions of the moirˊe supercell, may open a gap of over 100~meV, which is further confirmed by first-principles calculations. Our results provide a theoretical guidance for experiments to open a large gap in twisted bilayer graphene.
@article{arxiv.2403.14387,
title = {Tunable band gap in twisted bilayer graphene},
author = {Xiu-Cai Jiang and Yi-Yuan Zhao and Yu-Zhong Zhang},
journal= {arXiv preprint arXiv:2403.14387},
year = {2024}
}