2018/11/01 by Xianqing Lin, Dan Liu, Dan Liŭ +1
Chemistry · Materials Science · Physics and Astronomy · #2D Materials and Applications #Approx #Bilayer #Bilayer graphene #Chemistry #Condensed matter physics #Electronic band structure #Electronic structure #Fermi level #Geometry #Graphene #Graphene research and applications #Instability #Materials science #Physics #Quantum and electron transport phenomena #Quantum mechanics #Twist #cond-mat.mes-hall
paper · pdf · doi:10.1103/physrevb.98.195432
published as Phys. Rev. B 98 (2018) 195432 · Phys. Rev. B 98 (2018) (in press). 8 pages, 6 figures
arxiv created 2018/11/01 · openalex created_date 2018/11/09 · openalex publication_date 2018/11/21 · arxiv updated 2018/11/26 · openalex updated_date 2026/08/05
In twisted bilayer graphene (TBLG), extremely small deviations from the magic twist angle \ensuremathθm\ensuremath≈1.08^\ensuremath∘ change its electronic structure near the Fermi level drastically, causing a meV-wide flat band to appear or disappear. In view of such sensitivity to minute structural deformations, we investigate the combined effect of shear and atomic relaxation on the electronic structure. Using precise experimental data for monolayer and bilayer graphene as input in a simplified formalism for the electronic structure and elastic energy, we find TBLG near \ensuremathθm to be unstable with respect to global shear by the angle \ensuremathα\ensuremath≈0.08^\ensuremath∘. In TBLG, the effect of shear on the electronic structure is as important as that of atomic relaxation. Under optimum global shear, calculated \ensuremathθm is reduced by 0.04^\ensuremath∘ and agrees with the observed value.