Correlated phases and topological phase transition in twisted bilayer graphene at one quantum of magnetic flux

Abstract

When the perpendicular magnetic flux per unit cell in a crystal is equal to the quantum of magnetic flux, ${\Phi }_0=h/e$, we enter the 'Hofstadter regime'. The large unit cell of moiré materials like magic-angle twisted bilayer graphene (MATBG) allows the experimental study of this regime at feasible values of the field around $20$ to $30$ T. In this work, we report numerical analysis of a tight-binding model for MATBG at one quantum of external magnetic flux, including the long-range Coulomb and on-site Hubbard interaction. We study the correlated states for dopings of $-2,0$ and $2$ electrons per unit cell at the mean-field level. We find competing insulators with Chern numbers $2$ and $0$ at positive doping, the stability of which is determined by the dielectric screening, which opens up the possibility of observing a topological phase transition in this system.

Main text 8 pages, 4 figures. Appendices 9 pages, 7 figures. Published version. arXiv admin note: substantial text overlap with arXiv:2308.01997

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Cited by in corpus (4)

• Nematic versus Kekulé phases in twisted bilayer graphene under hydrostatic pressure
• Nonflat bands and chiral symmetry in magic-angle twisted bilayer graphene
• Review of the tight-binding method applicable to the properties of moiré superlattices
• Topological Phase Transitions of Interacting Fermions in the Presence of a Commensurate Magnetic Flux