Pons, R. and Mielke, A. and Stauber, T. (2020) Flat-band ferromagnetism in twisted bilayer graphene. PHYSICAL REVIEW B, 102 (23): 235101. ISSN 2469-9950, 2469-9969
Full text not available from this repository.Abstract
We discuss twisted bilayer graphene (TBG) based on a theorem of flat-band ferromagnetism put forward by Mielke and Tasaki. According to this theorem, ferromagnetism occurs if the single-particle density matrix of the flat-band states is irreducible and we argue that this result can be applied to the quasi-flat-bands of TBG that emerge around the charge-neutrality point for twist angles around the magic angle theta similar to 1.05 degrees. We show that the density matrix is irreducible in this case, thus predicting a ferromagnetic ground state for neutral TBG (n = 0). We then show that the theorem can also be applied only to the flat conduction or valence bands, if the substrate induces a single-particle gap at charge neutrality. Also in this case, the corresponding density matrix turns out to be irreducible, leading to ferromagnetism at half filling (n = +/- 2).
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | ; |
| Subjects: | 500 Science > 530 Physics |
| Divisions: | Physics > Institute of Theroretical Physics |
| Depositing User: | Dr. Gernot Deinzer |
| Date Deposited: | 08 Mar 2021 07:23 |
| Last Modified: | 08 Mar 2021 07:23 |
| URI: | https://pred.uni-regensburg.de/id/eprint/43304 |
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