Nearly flat bands in twisted triple bilayer graphene

Abstract

We investigate the electronic structure of alternating-twist triple Bernal-stacked bilayer graphene (t3BG) as a function of interlayer coupling $\omega$, twist angle $\theta$, interlayer potential difference $\Delta$, and top-bottom bilayers sliding vector $\mathbf{\tau }$ for three possible configurations AB/AB/AB, AB/BA/AB, and AB/AB/BA. The parabolic low-energy band dispersions in a Bernal-stacked bilayer and gap-opening through a finite interlayer potential difference $\Delta$ allows the flattening of bands in t3BG down to $\sim 20$~meV for twist angles $\theta \lesssim 2^{\circ }$ regardless of the stacking types. The easier isolation of the flat bands and associated reduction of Coulomb screening thanks to the intrinsic gaps of bilayer graphene for finite $\Delta$ facilitate the formation of correlation-driven gaps when it is compared to the metallic phases of twisted trilayer graphene under electric fields. We obtain the stacking dependent Coulomb energy versus bandwidth $U/W\gtrsim 1$ ratios in the $\theta$ and $\Delta$ parameter space. We also present the expected $K$-valley Chern numbers for the lowest-energy nearly flat bands.

15 pages, 10 figures

References in corpus (13)

• Tunable Phase Boundaries and Ultra-Strong Coupling Superconductivity in Mirror Symmetric Magic-Angle Trilayer Graphene
• Ab Initio Theory of Gate Induced Gaps in Graphene Bilayers
• Electric field tunable unconventional superconductivity in alternating twist magic-angle trilayer graphene
• Superlattice-induced insulating states and valley-protected orbits in twisted bilayer graphene
• Flatbands in twisted double bilayer graphene
• Band structure and topological property of twisted double bilayer graphenes
• Flat bands and perfect metal in trilayer moiré graphene
• Electronic Properties of Twisted Trilayer Graphene
• Gate tunable topological flat bands in twisted monolayer-bilayer graphene
• Electrical band flattening, valley flux, and superconductivity in twisted trilayer graphene
• Moiré pattern interlayer potentials in van der Waals materials from random-phase approximation calculations
• Lattice relaxation, mirror symmetry and magnetic field effects on ultraflat bands in twisted trilayer graphene
• Magic-Angle Multilayer Graphene: A Robust Family of Moiré Superconductors

Cited by in corpus (4)

• Electronic structure of biased alternating-twist multilayer graphene
• Tunable atomically enhanced moiré Berry curvatures in twisted triple bilayer graphene
• Orbital Hall Conductivity in a Graphene/Haldane and Haldane/Haldane Bilayers
• Sliding-dependent electronic structures of alternating-twist tetralayer graphene