The Many-Body Ground State Manifold of Flat Band Interacting Hamiltonian for Magic Angle Twisted Bilayer Graphene

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Hauptverfasser: Stubbs, Kevin D., Ragone, Michael, MacDonald, Allan H., Lin, Lin
Format: Preprint
Veröffentlicht: 2025
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author Stubbs, Kevin D.
Ragone, Michael
MacDonald, Allan H.
Lin, Lin
author_facet Stubbs, Kevin D.
Ragone, Michael
MacDonald, Allan H.
Lin, Lin
contents At a magic relative twist angle, magic angle twisted bilayer graphene (MATBG) has an octet of flat bands that can host strong correlation physics when partially filled. A key theoretical discovery in MATBG is the existence of ferromagnetic Slater determinants as exact ground states of the corresponding flat band interacting (FBI) Hamiltonian. The FBI Hamiltonian describes the behavior of electrons that interact with each other in a high-dimensional space, and is constructed from the band structure of the non-interacting Bistritzer--MacDonald model at the chiral limit. A key property of the FBI Hamiltonian for MATBG is that it is frustration free and can be written as a sum of non-commuting terms. In this work, we provide a complete characterization of the ground state manifold of the FBI Hamiltonian, proving that it is precisely the linear span of such ferromagnetic Slater determinants.
format Preprint
id arxiv_https___arxiv_org_abs_2503_20060
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle The Many-Body Ground State Manifold of Flat Band Interacting Hamiltonian for Magic Angle Twisted Bilayer Graphene
Stubbs, Kevin D.
Ragone, Michael
MacDonald, Allan H.
Lin, Lin
Mathematical Physics
Mesoscale and Nanoscale Physics
Strongly Correlated Electrons
At a magic relative twist angle, magic angle twisted bilayer graphene (MATBG) has an octet of flat bands that can host strong correlation physics when partially filled. A key theoretical discovery in MATBG is the existence of ferromagnetic Slater determinants as exact ground states of the corresponding flat band interacting (FBI) Hamiltonian. The FBI Hamiltonian describes the behavior of electrons that interact with each other in a high-dimensional space, and is constructed from the band structure of the non-interacting Bistritzer--MacDonald model at the chiral limit. A key property of the FBI Hamiltonian for MATBG is that it is frustration free and can be written as a sum of non-commuting terms. In this work, we provide a complete characterization of the ground state manifold of the FBI Hamiltonian, proving that it is precisely the linear span of such ferromagnetic Slater determinants.
title The Many-Body Ground State Manifold of Flat Band Interacting Hamiltonian for Magic Angle Twisted Bilayer Graphene
topic Mathematical Physics
Mesoscale and Nanoscale Physics
Strongly Correlated Electrons
url https://arxiv.org/abs/2503.20060