Bernal bilayer graphene exhibits a band gap that is tunable through the infrared with an electric field. We show that sublattice odd commensurate twisted bilayer graphene (C-TBG) exhibits a band gap that is tunable through the terahertz with an electric field. We show that from the perspective of terahertz optics the sublattice odd and even forms of C-TBG are "inflated" versions of Bernal and AA stacked bilayer graphene respectively with energy scales reduced by a factor of 110 for the 21.79 degree commensurate unit cell. This lower energy scale is accompanied by a correspondingly smaller gate voltage, which means that the strong-field regime is more easily accessible than in the Bernal case. Finally, we show that the interlayer coherence energy is a directly accessible experimental quantity through the position of a power-law divergence in the optical conductivity.
@article{arxiv.2212.00549,
title = {Electric Field Tunable Band Gap in Commensurate Twisted Bilayer Graphene},
author = {Spenser Talkington and Eugene J. Mele},
journal= {arXiv preprint arXiv:2212.00549},
year = {2026}
}
Comments
4+1 pages, 2 figures; v2 is final published version; v3 adds supplement