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TT: Fachverband Tiefe Temperaturen
TT 39: Twisted Materials / Systems (joint session TT/HL)
TT 39.2: Vortrag
Mittwoch, 19. März 2025, 17:15–17:30, H31
Nematic versus Kekulé phases in twisted bilayer graphene under hydrostatic pressure — Miguel Sánchez Sánchez1, Israel Díaz1, José González2, and •Tobias Stauber1 — 1Instituto de Ciencia de Materiales de Madrid, CSIC — 2Instituto de Ciencia de Materiales, CSIC
We address the precise determination of the phase diagram of magic angle twisted bilayer graphene under hydrostatic pressure within a self-consistent Hartree-Fock method in real space, including all the remote bands of the system. We further present a novel algorithm that maps the full real-space density matrix to a 4x4 density matrix based on a SU(4) symmetry of sublattice and valley degrees of freedom. We find a quantum critical point between a nematic and a Kekulé phase, and show also that our microscopic approach displays a strong particle-hole asymmetry in the weak coupling regime. We arrive then at the prediction that the superconductivity should be Ising-like in the hole-doped nematic regime, with spin-valley locking, and spin-triplet in the electron-doped regime [1].
[1] M. Sánchez Sánchez, I. Díaz, J. González, T. Stauber, Phys. Rev. Lett. (in press), arXiv:2403.03140.
Keywords: twisted bilayer graphene; correlated insulator phases; unconventional superconductivity