Topological Flat Bands and Correlated States in Twisted Monolayer-Bilayer Graphene

Abstract

Monolayer graphene placed with a twist on top of AB-stacked bilayer graphene hosts topological flat bands in a wide range of twist angles. The dispersion of these bands and gaps between them can be efficiently controlled by a perpendicular electric field, which induces topological transitions accompanied by changes of the Chern numbers. In the regime where the applied electric field induces gaps between the flat bands, we find a relatively uniform distribution of the Berry curvature. Consequently, interaction-induced valley- and/or spin-polarized states at integer filling factors are energetically favorable. In particular, we predict a quantum anomalous Hall state at filling factor $\nu =1$ for a range of twist angles $1^{\circ }<\theta <1.4^{\circ }$. Furthermore, to characterize the response of the system to magnetic field, we computed the Hofstadter butterfly and the Wannier plot, which can be used to probe the dispersion and topology of the flat bands in this material.

5 pages, 4 figures

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• Recent Developments in Fractional Chern Insulators
• Lattice relaxation, mirror symmetry and magnetic field effects on ultraflat bands in twisted trilayer graphene
• Spectroscopic visualization of flat bands in magic-angle twisted monolayer-bilayer graphene: localization-delocalization coexisting electronic states
• Proximity spin-orbit and exchange coupling in ABA and ABC trilayer graphene van der Waals heterostructures
• Emergent correlated phases in rhombohedral trilayer graphene induced by proximity spin-orbit and exchange coupling
• Local spectroscopy of a gate-switchable moiré quantum anomalous Hall insulator
• Moire Band Structures of the Double twisted Few Layer Graphene
• Observation of dichotomic field-tunable electronic structure in twisted monolayer-bilayer graphene
• Chern-insulator phases and spontaneous spin and valley order in a moiré lattice model for magic-angle twisted bilayer graphene
• Energy Spectrum Theory of Incommensurate Systems
• Perpendicular electronic transport and moiré-induced resonance in twisted interfaces of three-dimensional graphite
• Shift current response in twisted double bilayer graphenes
• Higher Chern bands in helical homotrilayer transition metal dichalcogenides
• Zero Indirect Band Gap and Flat Bands in a Niobium Oxyiodide Cluster Material