Scientific article
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Charge-transfer insulation in twisted bilayer graphene

Published inPhysical review. B, vol. 98, no. 23, 235158
Publication date2018-12-26
First online date2018-12-26
Abstract

We studied the real-space structure of states in twisted bilayer graphene at the magic angle θ=1.08∘. The flat bands close to charge neutrality are composed of a mix of “ring” and “center” orbitals around the AA stacking region. An effective model with localized orbitals is constructed which necessarily includes more than just the four flat bands. Long-range Coulomb interaction causes a charge transfer at half filling of the flat bands from the center to the ring orbitals. Consequently, the Mott phase is a featureless spin-singlet paramagnet. We estimate the effective Heisenberg coupling that favors the singlet coupling to be J=3.3 K, consistent with experimental values. The superconducting state depends on the nature of the dopants: hole-doping yields (p+ip)-wave, whereas electron-doping yields (d+id)-wave pairing symmetry.

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Citation (ISO format)
RADEMAKER, Louk, MELLADO, Paula. Charge-transfer insulation in twisted bilayer graphene. In: Physical review. B, 2018, vol. 98, n° 23, p. 235158. doi: 10.1103/PhysRevB.98.235158
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Additional URL for this publicationhttps://link.aps.org/doi/10.1103/PhysRevB.98.235158
Journal ISSN2469-9950
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