DMFT-QE Symposium: March 11

Talk 1:

The unconventional normal state of twisted bilayer graphene

María José Calderón, Instituto de Ciencia de Materiales de Madrid (CSIC)

Twisted bilayer Graphene (TBG) shows a great variety of correlated states such as superconducting, insulating, magnetic or intervalley coherent phases. Among the experimental observations, the cascades in the spectroscopic properties [1] and in the compressibility [2] happen in larger ranges of energy, twist angle and temperature than other effects, pointing to a hierarchy of phenomena. In this talk I will show that the origin of the cascades is associated to the formation of local moments and heavy quasiparticles and not to the symmetry breaking orders [3]. Our results are based on Dynamical Mean Field Theory plus Hartree calculations. We reproduce the cascade flow of spectral weight, the oscillations of the remote band energies, the asymmetric jumps of the inverse compressibility, and the presence of resistive states. We predict a strong momentum differentiation in the incoherent spectral weight associated to the fragile topology of TBG. I will also show how strong correlations impact other measurements that can be performed in order to characterize the unconventional normal state of these moiré systems.

[1] D. Wong et al, Nature 582, 198 (2020); Y. Choi et al, Nature 589, 536 (2021).
[2] U. Zondiner et al, Nature 582, 203 (2020).
[3] A. Datta, A. Camjayi, M.J. Calderón and E. Bascones, Nature Communications 14, 5036 (2023)

Talk 2:

Dynamical correlations and order in twisted bilayer graphene

Gautam Rai, Universität Hamburg