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Article: Polynomial sign problem and topological Mott insulator in twisted bilayer graphene

TitlePolynomial sign problem and topological Mott insulator in twisted bilayer graphene
Authors
Issue Date2023
Citation
Physical Review B, 2023, v. 107, n. 24, article no. L241105 How to Cite?
AbstractWe show that for the magic-angle twisted bilayer graphene (TBG) away from the charge neutrality point, although quantum Monte Carlo (QMC) simulations suffer from the sign problem, the computational complexity is at most polynomial at integer fillings of the flat-band limit. For even-integer fillings, the polynomial complexity survives even if an extra intervalley attractive interaction is introduced. This observation allows us to simulate magic-angle TBG and to obtain an accurate phase diagram and dynamical properties. At the chiral limit and filling ν=1, the simulations reveal a thermodynamic transition separating the metallic state and a C=1 correlated Chern insulator - topological Mott insulator (TMI) - and the pseudogap spectrum slightly above the transition temperature. The ground state excitation spectra of the TMI exhibit a spin-valley U(4) Goldstone mode and a time-reversal restoring excitonic gap smaller than the single-particle gap. These results are qualitatively consistent with recent experimental findings at zero-field and ν=1 filling in h-BN nonaligned TBG devices.
Persistent Identifierhttp://hdl.handle.net/10722/330329
ISSN
2023 Impact Factor: 3.2
2023 SCImago Journal Rankings: 1.345
ISI Accession Number ID

 

DC FieldValueLanguage
dc.contributor.authorZhang, Xu-
dc.contributor.authorPan, Gaopei-
dc.contributor.authorChen, Bin Bin-
dc.contributor.authorLi, Heqiu-
dc.contributor.authorSun, Kai-
dc.contributor.authorMeng, Zi Yang-
dc.date.accessioned2023-09-05T12:09:39Z-
dc.date.available2023-09-05T12:09:39Z-
dc.date.issued2023-
dc.identifier.citationPhysical Review B, 2023, v. 107, n. 24, article no. L241105-
dc.identifier.issn2469-9950-
dc.identifier.urihttp://hdl.handle.net/10722/330329-
dc.description.abstractWe show that for the magic-angle twisted bilayer graphene (TBG) away from the charge neutrality point, although quantum Monte Carlo (QMC) simulations suffer from the sign problem, the computational complexity is at most polynomial at integer fillings of the flat-band limit. For even-integer fillings, the polynomial complexity survives even if an extra intervalley attractive interaction is introduced. This observation allows us to simulate magic-angle TBG and to obtain an accurate phase diagram and dynamical properties. At the chiral limit and filling ν=1, the simulations reveal a thermodynamic transition separating the metallic state and a C=1 correlated Chern insulator - topological Mott insulator (TMI) - and the pseudogap spectrum slightly above the transition temperature. The ground state excitation spectra of the TMI exhibit a spin-valley U(4) Goldstone mode and a time-reversal restoring excitonic gap smaller than the single-particle gap. These results are qualitatively consistent with recent experimental findings at zero-field and ν=1 filling in h-BN nonaligned TBG devices.-
dc.languageeng-
dc.relation.ispartofPhysical Review B-
dc.titlePolynomial sign problem and topological Mott insulator in twisted bilayer graphene-
dc.typeArticle-
dc.description.naturelink_to_subscribed_fulltext-
dc.identifier.doi10.1103/PhysRevB.107.L241105-
dc.identifier.scopuseid_2-s2.0-85163482742-
dc.identifier.volume107-
dc.identifier.issue24-
dc.identifier.spagearticle no. L241105-
dc.identifier.epagearticle no. L241105-
dc.identifier.eissn2469-9969-
dc.identifier.isiWOS:001055183000001-

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