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arXiv · 2212.00549

Electric Field Tunable Band Gap in Commensurate Twisted Bilayer Graphene

Spenser Talkington·Eugene J. Mele
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Abstract

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.

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Spenser Talkington, Eugene J. Mele. 2022-12-01. Electric Field Tunable Band Gap in Commensurate Twisted Bilayer Graphene. https://doi.org/10.1103/physrevb.107.l041408

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