Dresden 2020 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 28: Twisted Bilayer Graphene (joint session TT/HL)

TT 28.2: Talk

Tuesday, March 17, 2020, 14:15–14:30, HSZ 201

Quantum capacitive coupling in large-angle twisted graphene layers — •Ming-Hao Liu — Department of Physics, National Cheng Kung University, Tainan, Taiwan

Magic-angle twisted bilayer graphene (tBLG) has revealed exotic physics of strong correlation in graphene systems and attracted enormous attention on twistronics of 2D materials. In the opposite extreme of large twist angles, relatively less attention has been paid. Due to the required large momentum change, scattering between different graphene layers of large-angle tBLG is forbidden. Through quantum capacitance of individual graphene layers, however, tBLG is electrostatically coupled, though electronically decoupled. Here, I introduce a self-consistent electrostatic model for carrier densities in decoupled tBLG systems and apply the model to perform quantum transport simulations for a recent experiment on a dual-gated large-angle tBLG device [1]. Good agreement between the experiment and theory confirms the electronic decoupling and indicates that the decoupled large-angle tBLG can be the thinnest parallel-plate capacitor in the world. The model can be further generalized to multi-layer systems composed of decoupled graphene sheets.

[1] P. Rickhaus et al., arXiv:1907.00582 (2019).