Phase Diagram and Spectroscopy of Twisted Bilayer Graphene: Correlations, Order, and Lattice Distorsions
ORAL · Invited
Abstract
Twisted bilayer graphene (TBG) hosts a remarkably rich set of correlated phases. Currently, a unified theoretical description of its many spectroscopic, thermodynamic, and ordering properties is far from complete.
Relevant progress in this direction has been made by employing the toolbox of strongly correlated electron systems, especially Dynamical Mean-Field Theory (DMFT).
In this talk, I will present the results of our microscopic many-body simulations, which combine dynamical correlation effects with spontaneous flavor symmetry breaking, heterostrain, and lattice relaxation.
This modeling framework reveals how these intertwined ingredients cooperatively shape the electronic spectra and phase diagram of TBG, naturally reproducing key experimental observations, from Scanning Tunneling and Quantum Twisting Microscopy to entropy and transport measurements.
Our results show doping- and temperature-controlled gap openings associated with interaction-driven symmetry breaking, providing a direct link between microscopic order and experimentally observed spectral reconstruction. In presence of lattice distortion effects, electronic correlations correctly account for three ubiquitous but previously unexplained experimental features: the persistence of finite-bias spectral peaks, the strong particle–hole asymmetry of the electronic compressibility, and the reduction of local-moment degeneracy at low temperatures.
Finally, I will provide initial evidence on the nature of superconductivity in TBG, detailing how it emerges out of a broken flavor symmetry normal state.
Altogether, these results establish a coherent microscopic understanding of how correlations, order, strain, and relaxation govern the behavior of TBG and related moiré materials.
Relevant progress in this direction has been made by employing the toolbox of strongly correlated electron systems, especially Dynamical Mean-Field Theory (DMFT).
In this talk, I will present the results of our microscopic many-body simulations, which combine dynamical correlation effects with spontaneous flavor symmetry breaking, heterostrain, and lattice relaxation.
This modeling framework reveals how these intertwined ingredients cooperatively shape the electronic spectra and phase diagram of TBG, naturally reproducing key experimental observations, from Scanning Tunneling and Quantum Twisting Microscopy to entropy and transport measurements.
Our results show doping- and temperature-controlled gap openings associated with interaction-driven symmetry breaking, providing a direct link between microscopic order and experimentally observed spectral reconstruction. In presence of lattice distortion effects, electronic correlations correctly account for three ubiquitous but previously unexplained experimental features: the persistence of finite-bias spectral peaks, the strong particle–hole asymmetry of the electronic compressibility, and the reduction of local-moment degeneracy at low temperatures.
Finally, I will provide initial evidence on the nature of superconductivity in TBG, detailing how it emerges out of a broken flavor symmetry normal state.
Altogether, these results establish a coherent microscopic understanding of how correlations, order, strain, and relaxation govern the behavior of TBG and related moiré materials.
–
Publication: [1] H. Hu et al, Phys. Rev. Lett. 131, 166501(2023)
[2] G. Rai et al, Phys. Rev. X 14, 031045 (2024)
[3] H. Kim et al, arXiv:2505.17200
[4] L. Crippa et al, arXiv:2509.19436
Presenters
-
Lorenzo Crippa
- Julius-Maximilians University of Wuerzburg
- University of Hamburg