2020/05/04 by Youngju Park, Bheema Lingam Chittari, Jeil Jung
Chemistry · Materials Science · Physics and Astronomy · #Bilayer #Bilayer graphene #Chemistry #Condensed matter physics #Coulomb #Electric field #Electron #Geometry #Graphene #Graphene research and applications #Materials science #Monolayer #Nanotechnology #Perpendicular #Physics #Quantum and electron transport phenomena #Quantum mechanics #Topological Materials and Phenomena #Twist #cond-mat.mes-hall
paper · pdf · doi:10.1103/physrevb.102.035411
published as Phys. Rev. B 102, 035411 (2020) · 15 pages, 11 figures
arxiv created 2020/05/04 · openalex created_date 2020/05/13 · openalex publication_date 2020/07/08 · arxiv updated 2020/07/15 · openalex updated_date 2026/08/05
We investigate the band structure of twisted monolayer-bilayer graphene (tMBG) trilayers, or twisted graphene on bilayer graphene, as a function of twist angles and perpendicular electric fields in search of optimal conditions for achieving isolated nearly flat bands. Narrow bandwidths comparable to or smaller than the effective Coulomb energies satisfying Ueff/W\ensuremath\gtrsim1 are expected for twist angles in the range of 0.3^\ensuremath∘--1.5^\ensuremath∘, more specifically in islands around \ensuremathθ\ensuremath∼0.5^\ensuremath∘,0.85^\ensuremath∘,1.3^\ensuremath∘ for appropriate perpendicular electric field magnitudes and directions. The valley Chern numbers of the electron-hole asymmetric bands depend intrinsically on the details of the hopping terms in the bilayer graphene, and extrinsically on factors like electric fields or average staggered potentials in the graphene layer aligned with the contacting hexagonal boron nitride substrate. This tunability of the band isolation, bandwidth, and valley Chern numbers makes tMBG trilayers a more versatile system than twisted bilayer graphene for finding nearly flat bands prone to strong correlations.