In:
2D Materials, IOP Publishing, Vol. 8, No. 2 ( 2021-04-01), p. 025025-
Abstract:
We study the stability and electronic structure of magic-angle twisted bilayer graphene on the hexagonal boron nitride (TBG/BN). Structural relaxation has been performed for commensurate supercells of the heterostructures with different twist angles ( θ ′ ) and stackings between TBG and BN. We find that the slightly misaligned configuration with θ ′ = 0.54 ∘ and the AA/AA stacking has the globally lowest total energy due to the constructive interference of the moiré interlayer potentials and thus the greatly enhanced relaxation in its 1 × 1 commensurate supercell. Gaps are opened at the Fermi level ( E F ) for small supercells with the stackings that enable strong breaking of the C 2 symmetry in the atomic structure of TBG. For large supercells with θ ′ close to those of the 1 × 1 supercells, the broadened flat bands can still be resolved from the spectral functions. The θ ′ = 0.54 ∘ is also identified as a critical angle for the evolution of the electronic structure with θ ′ , at which the energy range of the mini-bands around E F begins to become narrower with increasing θ ′ and their gaps from the dispersive bands become wider. The discovered stablest TBG/BN with a finite θ ′ of about 0.54 ∘ and its gapped flat bands agree with recent experimental observations.
Type of Medium:
Online Resource
ISSN:
2053-1583
DOI:
10.1088/2053-1583/abddcb
Language:
Unknown
Publisher:
IOP Publishing
Publication Date:
2021
detail.hit.zdb_id:
2779376-X
