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Weak-coupling theory of magic-angle twisted bilayer graphene

Jihang Zhu1,2, Iacopo Torre3, Marco Polini4,5,3, and A. H. MacDonald6

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Phys. Rev. B 110, L121117 – Published 20 September, 2024

DOI: https://doi.org/10.1103/PhysRevB.110.L121117

Abstract

Strong correlations occur in magic-angle twisted bilayer graphene (MATBG) when the octet of flat moiré minibands centered on charge neutrality (CN) is partially occupied. The octet consists of a single valence band and a single conduction band for each of four degenerate spin-valley flavors. Motivated by the importance of Hartree electrostatic interactions in determining the filling-factor-dependent band structure, we use a time-dependent Hartree approximation to gain insight into electronic correlations. We find that the electronic compressibility is dominated by Hartree interactions, that paramagnetic states are stable over a range of density near CN, and that the dependence of energy on flavor polarization is strongly overestimated by mean-field theory.

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Phys. Rev. B 110, L121117– Published 20 September, 2024
  • Received 21 December 2023
  • Revised 30 July 2024
  • Accepted 6 September 2024
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