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| Format: | Preprint |
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2024
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| Online-Zugang: | https://arxiv.org/abs/2404.08177 |
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| _version_ | 1866909565696606208 |
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| author | Vidarte, Kevin J. U. Riffo, Felipe Pérez Morell, Eric Suárez Lewenkopf, Caio |
| author_facet | Vidarte, Kevin J. U. Riffo, Felipe Pérez Morell, Eric Suárez Lewenkopf, Caio |
| contents | We present a theoretical investigation of the magnetic properties exhibited by twisted bilayer graphene (TBG) systems with small twist angles, where the appearance of flat minibands strongly enhances electron-electron interaction effects. We show that, at three-quarters filling of the conduction miniband, the Stoner mechanism induces a ferromagnetic polarization in the AA-stacking regions, which aligns with recent experimental observations. Our approach models the electronic properties by a tight-binding Hamiltonian combined with a Hubbard mean-field interaction term. We employ a real-space recursion technique to self-consistently calculate the system's local density of states and use our method to investigate the magnetic properties of small-angle TBG at three-quarters filling. The recursion method's $O({\cal N})$ efficiency makes it possible to address extremely large superlattices through a full real-space approach. We validate our procedure by comparing it with mean-field momentum-space calculations from the literature, which identify a magnetic phase in charge-neutral TBGs. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2404_08177 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Stoner ferromagnetism in low-angle twisted bilayer graphene at three-quarters filling Vidarte, Kevin J. U. Riffo, Felipe Pérez Morell, Eric Suárez Lewenkopf, Caio Mesoscale and Nanoscale Physics We present a theoretical investigation of the magnetic properties exhibited by twisted bilayer graphene (TBG) systems with small twist angles, where the appearance of flat minibands strongly enhances electron-electron interaction effects. We show that, at three-quarters filling of the conduction miniband, the Stoner mechanism induces a ferromagnetic polarization in the AA-stacking regions, which aligns with recent experimental observations. Our approach models the electronic properties by a tight-binding Hamiltonian combined with a Hubbard mean-field interaction term. We employ a real-space recursion technique to self-consistently calculate the system's local density of states and use our method to investigate the magnetic properties of small-angle TBG at three-quarters filling. The recursion method's $O({\cal N})$ efficiency makes it possible to address extremely large superlattices through a full real-space approach. We validate our procedure by comparing it with mean-field momentum-space calculations from the literature, which identify a magnetic phase in charge-neutral TBGs. |
| title | Stoner ferromagnetism in low-angle twisted bilayer graphene at three-quarters filling |
| topic | Mesoscale and Nanoscale Physics |
| url | https://arxiv.org/abs/2404.08177 |