Dresden 2026 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 4: Graphene, 2D and Twisted Materials
TT 4.2: Vortrag
Montag, 9. März 2026, 09:45–10:00, HSZ/0105
Non-collinear magnetism of flat bands in magic-angle twisted bilayer graphene — •Maxime Lucas1, Arnaud Ralko2, Andreas Honecker1, and Guy Trambly de Laissardière1 — 1Laboratoire de Physique Théorique et Modélisation, CY Cergy Paris Université / CNRS, France — 2Institut Néel, Université de Grenoble Alpes / CNRS, France
Recent advances of twisted bilayer graphene (and related moiré materials) have been stimulated by the discovery of strong electronic correlations [1] between flat-band states due to a moiré pattern [2]. It is shown experimentally and theoretically that the filling of the flat bands affects their magnetic properties significantly. Similar to what we have done in monolayer graphene [3], we investigate how electronic filling and on-site interactions drive magnetic ordering by studying a Hubbard model on the moiré lattice within an unrestricted Hartree-Fock framework. We mapped out a rich magnetic ground-state phase diagram and uncover a variety of exotic non-collinear spin textures.
[1] Y. Cao et al., Nature 556, 43 (2018); Nature 556, 80 (2018).
[2] G. Trambly de Laissardière et al., Physica E 175, 116362 (2026)
[3] M. Lucas et al., arXiv:2511.22714 [cond-mat.str-el] (2025)
Keywords: Twisted Bilayer Graphene; Magnetism; Hubbard model; Flat bands; Real-space Mean-field