Tunable optical property and flat bands in twisted double bilayer graphene

Luo, Guoyu; Wen, Lu; Lv, Xinyu; Li, Zhiqiang

doi:10.1016/j.physleta.2021.127670

Cited by 3 publications

(1 citation statement)

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“…The moiré superlattice formed by stacking two atom-thin materials with a twist angle introduces energy scales and new length, which provides a powerful way to control quantum phenomena in two-dimensional heterostrain [1][2][3][4][5][6][7][8][9][10][11][12]. Such a superlattice can greatly modify the energy band structure of the system [13][14][15][16][17]. As a result, moiré minibands form flat bands with a very high density of states at some twist angles, showing many novel quantum effects, such as superconductivity [5,18], correlated insulator phases [6], topological edge states [19,20], magnetism [21] and exciton trapping [22].…”

Section: Introductionmentioning

confidence: 99%

Flat bands and topological properties of twisted bilayer WSe₂ under external stimuli

Wang¹,

Yu²,

Guo-yu³

et al. 2022

Phys. Scr.

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We present calculations on electronic band structures and topological properties of the flat band of twisted bilayer WSe2 with twist angle near 1°, by using the effective continuum model under different heterostrain, pressure and vertical electric field. We find that the first valence band exhibit a narrow bandwidth and can be efficiently modified by heterostrain, where a much narrower bandwidth of this flat band can be achieved over a wide range of strain magnitudes. The energy gap between the first two valence bands is reduced by heterostrain while it is significantly enlarged under pressure and vertical electric field. Furthermore, the applied vertical electric field leads to topological transition in each valley for the first valence band. We give a feasible experiment proposal to reveal this phenomenon. Our results serve as a theoretical guide for exploring emergent correlated electron physics and topological physics in this versatile moiré superlattice system.

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