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  • Open Access

Buckling and flat bands in twisted bilayer graphene

Jannes van Poppelen* and Annica M. Black-Schaffer

  • Department of Physics and Astronomy, Uppsala University, Box 516, SE-75237 Uppsala, Sweden

  • *Contact author: jannes.vanpoppelen@physics.uu.se
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Phys. Rev. B 113, 115154 – Published 26 March, 2026

DOI: https://doi.org/10.1103/gcbz-xhdg

Abstract

Magic-angle twisted bilayer graphene (TBG) with its flat bands provides a rich platform for exploring emergent electronic orders. Similarly, periodically buckled monolayer graphene (MLG) has been proposed as a tunable alternative for realizing flat bands. Here, we investigate the combined effect of buckling and twisting in bilayer graphene. We find that periodic buckling in large-angle TBG initially enhances band flattening compared to monolayer graphene, but for sufficiently strong buckling, it instead increases the band dispersion. This occurs because of both the presence of interlayer coupling, which reduces the in-plane kinetic energy, and the opening of a gap at the Dirac point resulting from inversion-symmetry breaking. Additionally, we find that buckling-induced band flattening competes with twist-induced band flattening. While the former breaks sublattice symmetry, generating a sublattice polarization, the latter prefers to preserve it. This prevents buckling from generating even flatter bands at the magic angle. Nevertheless, we find that buckled TBG can exhibit flatter bands than pristine TBG over a wide range of twist angles, with a flatness similar to that of pristine magic-angle TBG.

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Outline

Information

Phys. Rev. B 113, 115154– Published 26 March, 2026
  • Received 17 October 2025
  • Revised 30 January 2026
  • Accepted 25 February 2026
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