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arXiv · 2403.14387

Tunable band gap in twisted bilayer graphene

Xiu-Cai Jiang·Yi-Yuan Zhao·Yu-Zhong Zhang
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Abstract

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 moi$\rm\acute{r}$e 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.

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Xiu-Cai Jiang, Yi-Yuan Zhao, Yu-Zhong Zhang. 2024-03-21. Tunable band gap in twisted bilayer graphene. https://doi.org/10.1103/physrevb.105.115106

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