Regensburg 2025 – scientific programme
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MA: Fachverband Magnetismus
MA 14: Focus Session: Strongly Correlated Quantum States in Moire Heterostructures (joint session TT/HL/MA)
MA 14.2: Topical Talk
Tuesday, March 18, 2025, 10:00–10:30, H36
Angle-Tuned Chiral Phase Transition in Twisted Bilayer Graphene — •Laura Classen1,2, Nikolaos Parthenios1,2, Cheng Huang3, Xu Zhang3, Maksim Ulybyshev4, Fakher Assaad3, and Zi Yang Meng4 — 1Max Planck Institute for Solid State Research — 2Technical University of Munich — 3University of Hong Kong — 4University of Wuerzburg
The twist angle constitutes an important control knob in twisted bilayer graphene that has become accessible in-situ. It effectively tunes between weakly interacting, decoupled graphene layers and strongly correlated electrons at a magic angle of around 1.1 degree. We propose that this facilitates the realisation of a chiral phase transition of Dirac fermions at charge neutrality in twisted bilayer graphene. We argue that the transition can be described by the Gross-Neveu-Yukawa model that couples Dirac fermions and an XY order parameter field. The quantum critical behavior of this effective model is consistent with quantum Monte Carlo simulations of the continuum model for twisted bilayer graphene.
Keywords: quantum criticality; moiré materials; strongly interacting Dirac fermions