Topological flat bands in rhombohedral tetralayer and multilayer graphene on hexagonal boron nitride moire superlattices

Abstract

We show that rhombohedral four-layer graphene (4LG) nearly aligned with a hexagonal boron nitride (hBN) substrate often develops nearly flat isolated low energy bands with non-zero valley Chern numbers. The bandwidths of the isolated flatbands are controllable through an electric field and twist angle, becoming as narrow as $\sim 10$meV for interlayer potential differences between top and bottom layers of $|\Delta |\approx 10\sim 15$meV and $\theta \sim 0.5^{\circ }$ at the graphene and boron nitride interface. The local density of states (LDOS) analysis shows that the nearly flat band states are associated to the non-dimer low energy sublattice sites at the top or bottom graphene layers and their degree of localization in the moire superlattice is strongly gate tunable, exhibiting at times large delocalization despite of the narrow bandwidth. We verified that the first valence bands' valley Chern numbers are $C_{V1}^{\nu =\pm 1}=\pm n$, proportional to layer number for $n$LG/BN systems up to $n=8$ rhombohedral multilayers.

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Cited by in corpus (19)

• Anomalous Hall Crystals in Rhombohedral Multilayer Graphene I: Interaction-Driven Chern Bands and Fractional Quantum Hall States at Zero Magnetic Field
• Theory of quantum anomalous Hall phases in pentalayer rhombohedral graphene moiré structures
• Superconductivity and quantized anomalous Hall in rhombohedral graphene
• Theory of fractional Chern insulator states in pentalayer graphene moiré superlattice
• Anomalous Hall Crystals in Rhombohedral Multilayer Graphene II: General Mechanism and a Minimal Model
• Parent Berry curvature and the ideal anomalous Hall crystal
• Moiré Fractional Chern Insulators III: Hartree-Fock Phase Diagram, Magic Angle Regime for Chern Insulator States, the Role of the Moiré Potential and Goldstone Gaps in Rhombohedral Graphene Superlattices
• Displacement field-controlled fractional Chern insulators and charge density waves in a graphene/hBN moiré superlattice
• Efficient prediction of superlattice and anomalous miniband topology from quantum geometry
• Quantum anomalous, spin, and valley Hall effects in pentalayer rhombohedral graphene moiré superlattices
• Reentrant topological phases and spin density wave induced by 1D moiré potentials
• Entropy-Enhanced Fractional Quantum Anomalous Hall Effect
• Promoting and imaging intervalley coherent order in rhombohedral tetralayer graphene on MoS2
• Real-space study of zero-field correlation in tetralayer rhombohedral graphene
• Orbital Hall Conductivity in a Graphene/Haldane and Haldane/Haldane Bilayers
• Elastic Response and Instabilities of Anomalous Hall Crystals
• Extended Haldane Model in The Dice Lattice: Multiple Flat-Band-Induced topological Transitions Revealed
• Gate and Carriers tunable Valley Imbalance in Topological Proximitized Rhombohedral Trilayer Graphene
• Higher Chern bands in helical homotrilayer transition metal dichalcogenides