On the Hartree-Fock Ground State Manifold in Magic Angle Twisted Graphene Systems

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Hauptverfasser: Stubbs, Kevin D., Becker, Simon, Lin, Lin
Format: Preprint
Veröffentlicht: 2024
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author Stubbs, Kevin D.
Becker, Simon
Lin, Lin
author_facet Stubbs, Kevin D.
Becker, Simon
Lin, Lin
contents Recent experiments have shown that magic angle twisted bilayer graphene (MATBG) can exhibit correlated insulator behavior at half-filling. Seminal theoretical results towards understanding this phase in MATBG has shown that Hartree-Fock ground states (with a positive charge gap) can be exact many-body ground states of an idealized flat band interacting (FBI) Hamiltonian. We prove that in the absence of spin and valley degrees of freedom, the only Hartree-Fock ground states of the FBI Hamiltonian for MATBG are two ferromagnetic Slater determinants. Incorporating spin and valley degrees of freedom, we provide a complete characterization of the Hartree-Fock ground state manifold, which is generated by a ${\rm U}(4) \times {\rm U}(4)$ hidden symmetry group acting on five elements. We also introduce new tools for ruling out translation symmetry breaking in the Hartree-Fock ground state manifold, which may be of independent interest.
format Preprint
id arxiv_https___arxiv_org_abs_2403_19890
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle On the Hartree-Fock Ground State Manifold in Magic Angle Twisted Graphene Systems
Stubbs, Kevin D.
Becker, Simon
Lin, Lin
Mathematical Physics
Mesoscale and Nanoscale Physics
Strongly Correlated Electrons
Recent experiments have shown that magic angle twisted bilayer graphene (MATBG) can exhibit correlated insulator behavior at half-filling. Seminal theoretical results towards understanding this phase in MATBG has shown that Hartree-Fock ground states (with a positive charge gap) can be exact many-body ground states of an idealized flat band interacting (FBI) Hamiltonian. We prove that in the absence of spin and valley degrees of freedom, the only Hartree-Fock ground states of the FBI Hamiltonian for MATBG are two ferromagnetic Slater determinants. Incorporating spin and valley degrees of freedom, we provide a complete characterization of the Hartree-Fock ground state manifold, which is generated by a ${\rm U}(4) \times {\rm U}(4)$ hidden symmetry group acting on five elements. We also introduce new tools for ruling out translation symmetry breaking in the Hartree-Fock ground state manifold, which may be of independent interest.
title On the Hartree-Fock Ground State Manifold in Magic Angle Twisted Graphene Systems
topic Mathematical Physics
Mesoscale and Nanoscale Physics
Strongly Correlated Electrons
url https://arxiv.org/abs/2403.19890