SKM 2023 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 61: Focus Session: Correlations in Moiré Quantum Matter II
TT 61.5: Vortrag
Donnerstag, 30. März 2023, 18:45–19:00, HSZ 201
Magnetism in twisted bilayer graphene with heterostrain — Ahmed Missaoui1, Florie Mesple2, Javad Vahedi3, Andreas Honecker1, Vincent Renard2, and •Guy Trambly de Laissardière1 — 1Laboratoire de Physique Théorique et Modélisation, CY Cergy Paris Université / CNRS, Cergy-Pontoise, France — 2Université Grenoble Alpes, CEA, Grenoble INP, IRIG, PHELIQS, Grenoble, France — 3Jacobs University, School of Engineering and Science, Bremen, Germany
The discovery of correlated insulators and superconductivity due to flat bands in twisted bilayer graphene (TBG) at so-called “magic angles” has stimulated the study of their magnetic properties [1]. Furthermore, it is now well established that heterostrain, which is generally present in the samples, is a key parameter in understanding the actual shape of the flat bands [2]. Here, we present a theoretical study of magnetism in magic-angle TBG combining a Hubbard model and the mean-filed approach including non-collinear magnetic terms. We show how heterostrain strongly modifies the magnetization and the local order of magnetic state for realistic Coulomb interaction values.
[1] J. Vahedi et al., SciPost Phys. 11, 083 (2021) and references therein
[2] L. Huder et al., Phys. Rev. Lett. 120, 156405 (2018);
F. Mesple et al., Phys. Rev. Lett. 127, 126405 (2021)