Electron-hole asymmetry and band gaps of commensurate double moire patterns in twisted bilayer graphene on hexagonal boron nitride

Abstract

Spontaneous orbital magnetism observed in twisted bilayer graphene (tBG) on nearly aligned hexagonal boron nitride (BN) substrate builds on top of the electronic structure resulting from combined G/G and G/BN double moire interfaces. Here we show that tBG/BN commensurate double moire patterns can be classified into two types, each favoring the narrowing of either the conduction or valence bands on average, and obtain the evolution of the bands as a function of the interlayer sliding vectors and electric fields. Finite valley Chern numbers $\pm 1$ are found in a wide range of parameter space when the moire bands are isolated through gaps, while the local density of states associated to the flat bands are weakly affected by the BN substrate invariably concentrating around the AA-stacked regions of tBG. We illustrate the impact of the BN substrate for a particularly pronounced electron-hole asymmetric band structure by calculating the optical conductivities of twisted bilayer graphene near the magic angle as a function of carrier density. The band structures corresponding to other $N$-multiple commensurate moire period ratios indicate it is possible to achieve narrow width $W\lesssim 30$ meV isolated folded band bundles for tBG angles $\theta \lesssim 1^{\circ }$.

17 pages, 9 figures

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Cited by in corpus (20)

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• An accurate description of the structural and electronic properties of twisted bilayer graphene-boron nitride heterostructures
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• Designing Moiré Patterns by Strain
• Emergence of broken-symmetry states at half-integer band fillings in twisted bilayer graphene
• Multi-scale lattice relaxation in general twisted trilayer graphenes
• Topological flat bands in rhombohedral tetralayer and multilayer graphene on hexagonal boron nitride moire superlattices
• Stacking and gate tunable topological flat bands, gaps and anisotropic strip patterns in twisted trilayer graphene
• Electronic properties of twisted bilayer graphene suspended and encapsulated with hexagonal boron nitride
• Fractal energy gaps and topological invariants in hBN/Graphene/hBN double moiré systems
• Electron-phonon coupling and competing Kekulé orders in twisted bilayer graphene
• Band gap formation in commensurate twisted bilayer graphene/hBN moiré lattices
• Atomistic theory of moiré Hofstadter's butterfly in magic-angle graphene
• Moiré Band Engineering in Twisted Trilayer WSe2
• Designing Moire Patterns by Shearing
• Collective excitations of the Chern-insulator states in commensurate double moiré superlattices of twisted bilayer graphene on hexagonal boron nitride
• Orbital Hall Conductivity in a Graphene/Haldane and Haldane/Haldane Bilayers
• One-dimensional moiré engineering in zigzag graphene nanoribbons on hBN
• Doping-induced Quantum Anomalous Hall Crystals and Topological Domain Walls