2025/08/18 by Sánchez, Miguel Sánchez, González, José, Stauber, Tobias · 1 citation
#FOS: Physical sciences #Mesoscale and Nanoscale Physics (cond-mat.mes-hall) #Strongly Correlated Electrons (cond-mat.str-el) #Superconductivity (cond-mat.supr-con)
paper · doi:10.48550/arxiv.2508.12825
We discuss the Fermi-velocity renormalization in twisted bilayer graphene due to Coulomb exchange interaction within an atomistic tight-binding model. Adopting the Slater-Koster parametrization for the hopping parameters obtained from first principles, our results only depend on the effective dielectric constant ε and the Hubbard-interaction U. The Fermi velocity of graphene increases twist-angle independent by ~25% for ε=10 and U=4eV, leading to an increase by more than 100% of the flat bandwidth at twist-angle θ=1.4^∘. Including also the renormalization of the out-of-plane hopping terms, we further observe a shift of the magic angle from 1.02^∘ to 0.96^∘. Our results offer a microscopic explanation of the critical temperature, Tc, as function of the twist angle where the largest Tc is found at θmax=1.1^∘. For θ>θmax, Tc is obtained from the Bethe-Salpeter equation of the Cooper channel. For θ<θmax, the discussion is based on the critical line of the Berezinskii-Kosterlitz-Thouless phase transition.