Strong Coupling Phases of Partially Filled Twisted Bilayer Graphene Narrow Bands

Jian Kang and Oskar Vafek
Phys. Rev. Lett. 122, 246401 – Published 18 June 2019
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Abstract

We identify states favored by Coulomb interactions projected onto the Wannier basis of the four narrow bands of the “magic angle” twisted bilayer graphene. At the filling of 2 electrons/holes per moiré unit cell, such interactions favor an insulating SU(4) ferromagnet. The kinetic terms select the ground state in which the two valleys with opposite spins are equally mixed, with a vanishing magnetic moment per particle. We also find extended excited states, the gap to which decreases in the magnetic field. An insulating stripe ferromagnetic phase is favored at 1 electron/hole per unit cell.

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  • Received 4 November 2018

DOI:https://doi.org/10.1103/PhysRevLett.122.246401

© 2019 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Jian Kang1,* and Oskar Vafek1,2,†

  • 1National High Magnetic Field Laboratory, Tallahassee, Florida, 32304, USA
  • 2Department of Physics, Florida State University, Tallahassee, Florida 32306, USA

  • *jian.kang@fsu.edu
  • vafek@magnet.fsu.edu

See Also

Ferromagnetic Mott state in Twisted Graphene Bilayers at the Magic Angle

Kangjun Seo, Valeri N. Kotov, and Bruno Uchoa
Phys. Rev. Lett. 122, 246402 (2019)

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Vol. 122, Iss. 24 — 21 June 2019

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