Band structure and insulating states driven by Coulomb interaction in twisted bilayer graphene

  title={Band structure and insulating states driven by Coulomb interaction in twisted bilayer graphene},
  author={Tommaso Cea and Francisco Guinea},
  journal={Physical Review B},
We analyze the phase diagram of twisted graphene bilayers near a magic angle. We consider the effect of the long-range Coulomb interaction, treated within the self-consistent Hartree-Fock approximation, and we study arbitrary band fillings. We find a rich phase diagram, with different broken symmetry phases, although they do not show necessarily a gap at the Fermi energy. There are nontrivial effects of the electrostatic potential on the shape and the gaps of the bands in the broken symmetry… Expand

Figures and Tables from this paper

Cascades between light and heavy fermions in the normal state of magic angle twisted bilayer graphene
We present a framework for understanding the recently observed cascade transitions and the Landau level degeneracies at every integer filling of twisted bilayer graphene. The Coulomb interactionExpand
Correlation-Induced Insulating Topological Phases at Charge Neutrality in Twisted Bilayer Graphene
Twisted bilayer graphene (TBG) provides a unique framework to elucidate the interplay between strong correlations and topological phenomena in two-dimensional systems. The existence of multipleExpand
Coulomb interaction, phonons, and superconductivity in twisted bilayer graphene
  • T. Cea, F. Guinea
  • Physics, Medicine
  • Proceedings of the National Academy of Sciences
  • 2021
The polarizability of twisted bilayer graphene, due to the combined effect of electron–hole pairs, plasmons, and acoustic phonons, is analyzed, emphasizing the tunability of superconductivity with the electronic band structure close to the Fermi level. Expand
Detecting symmetry breaking in magic angle graphene using scanning tunneling microscopy
A growing body of experimental work suggests that magic angle twisted bilayer graphene exhibits a “cascade” of spontaneous symmetry breaking transitions, sparking interest in the potentialExpand
Does filling-dependent band renormalization aid pairing in twisted bilayer graphene?
Magic-angle twisted bilayer graphene (MATBG) exhibits a panoply of many-body phenomena that are intimately tied to the appearance of narrow and well-isolated electronic bands. The microscopicExpand
Domain wall competition in the Chern insulating regime of twisted bilayer graphene
We consider magic-angle twisted bilayer graphene (TBG) at filling $\nu=+3$, where experiments have observed a robust quantized anomalous Hall effect. This has been attributed to the formation of aExpand
Fermionic Monte Carlo study of a realistic model of twisted bilayer graphene
The rich phenomenology of twisted bilayer graphene (TBG) near the magic angle is believed to arise from electron correlations in topological flat bands. An unbiased approach to this problem is highlyExpand
Gap generation and flat band catalysis in dice model with local interaction
The gap generation in the dice model with local four-fermion interaction is studied. Due to the presence of two valleys with degenerate electron states, there are two main types of gaps. The intraandExpand
Global phase diagram of twisted bilayer graphene above $T_c$
We investigate the full doping and strain-dependent phase diagram (absent superconductivity) of magic-angle twisted bilayer graphene (TBG). Using comprehensive Hartree-Fock calculations, we show thatExpand
Holographic construction of flat bands
Flat electronic bands have recently attracted a great deal of attention since they provide a platform hosting a plethora of interaction-driven quantum phases, as, for instance, experimentallyExpand


Graphene bilayer with a twist
  • Electronic structure, Phys. Rev. Lett. 99,
  • 2007
Time-reversal versus chiral symmetry breaking in twisted bilayer graphene
  • arXiv e-prints , arXiv:2002.12039
  • 2020
Chern bands of twisted bilayer graphene: Fractional Chern insulators and spin phase transition
When one of the graphene layers of Magic Angle Twisted Bilayer Graphene is nearly aligned with its hexagonal boron nitride substrate (a configuration dubbed TBG/hBN), the active electronic bands areExpand
and A
  • Vishwanath, Nematic topological semimetal and insulator in magic angle bilayer graphene at charge neutrality
  • 2019
and M
  • P. Zaletel, Ground state and hidden symmetry of magic angle graphene at even integer filling
  • 2019
Electrostatic effects
  • band distortions, and superconductivity in twisted graphene bilayers, Proceedings of the National Academy of Sciences 115, 13174
  • 2018
Maximally Localized Wannier Orbitals and the Extended Hubbard Model for Twisted Bilayer Graphene
We develop an effective extended Hubbard model to describe the low-energy electronic properties of the twisted bilayer graphene. By using the Bloch states in the effective continuum model and withExpand
Graphene integer quantum Hall effect in the ferromagnetic and paramagnetic regimes
Starting from the graphene lattice tight-binding Hamiltonian with an on-site U and long-range Coulomb repulsion, we derive an interacting continuum Dirac theory governing the low-energy behavior ofExpand
Electronic band structure and pinning of Fermi energy to Van Hove singularities in twisted bilayer graphene: A self-consistent approach
The emergence of flat bands in twisted bilayer graphene leads to an enhancement of interaction effects, and thus to insulating and superconducting phases at low temperatures, even though the exactExpand
Nematic topological semimetal and insulator in magic-angle bilayer graphene at charge neutrality
We report on a fully self-consistent Hartree-Fock calculation of interaction effects on the Moire flat bands of twisted bilayer graphene, assuming that valley U(1) symmetry is respected. We useExpand