Berlin 2024 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 37: Graphene and 2D Materials (joint session TT/HL)

TT 37.3: Talk

Wednesday, March 20, 2024, 10:00–10:15, H 3007

Fermi Velocity renormalization in graphene from large scale Quantum Monte Carlo simulations — •Maksim Ulybyshev¹, Savvas Zafeiropoulos², Christopher Winterowd³, and Fakher Assaad^{1, 4} — ¹Julius-Maximilians-Universität Würzburg, Germany — ²Aix Marseille Univ, Universite de Toulon, CNRS, CPT, Marseille, France — ³Johann Wolfgang Goethe-Universität Frankfurt am Main, Germany — ⁴Würzburg-Dresden Cluster of Excellence ct.qmat, Würzburg, Germany

Through recent advancements in algorithms, we extended the capabilities of unbiased Quantum Monte Carlo (QMC) simulations up to the lattices with spatial volume of 20808 sites. These simulations were applied to both suspended graphene and graphene on substrates, enabling direct comparison with experimental data without the need for additional extrapolations. This technique allowed us to successfully confront the numerical and experimental estimates of the Fermi velocity renormalization near the Dirac point.

Our findings validate the logarithmic divergence of the Fermi velocity, but also show the limitations of the low-energy continuum theory in quantitative description of this divergence. Additionally, our research demonstrates the significance of lattice-scale physics and higher-order perturbative corrections beyond the Random Phase Approximation (RPA) for a more accurate description of the experimental data for the Fermi velocity renormalization in suspended graphene. We also propose experimental approaches to demonstrate the role of higher-order perturbative corrections.

Keywords: Graphene; Strongly correlated electrons; Coulomb interaction