Dresden 2026 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 26: Transport in Materials: Diffusion, Charge, or Heat Conduction I
MM 26.5: Vortrag
Mittwoch, 11. März 2026, 16:45–17:00, SCH/A216
Effects of strong electron-electron interactions on the conductivity of free-standing graphene — •Maksim Ulybyshev1, Adrien Reingruber1, and Kitinan Pongsangangan2 — 1Institut für Theoretische Physik und Astrophysik, Universität Würzburg, Würzburg, Germany — 2Department of Physics, Faculty of Science, Mahidol University, Bangkok, Thailand
Transport in strongly correlated systems is often described using the Boltzmann equation, where correlation effects enter through the collision integral. In practice, the collision integral is usually evaluated with a number of approximations, such as computing scattering amplitudes only up to tree-level diagrams. These approximations become unreliable when interactions are sufficiently strong.
Free-standing graphene provides a representative example, as the effective coupling constant of its low-energy effective field theory exceeds unity. Using unbiased Quantum Monte Carlo (QMC) simulations on lattices with up to 102x102 unit cells and long-range Coulomb interactions, we investigate both the DC and optical conductivity of free-standing graphene. We find that the optical conductivity remains essentially unaffected by interactions, whereas the DC conductivity exhibits a strong dependence on both temperature and interaction strength. We then compare these results with kinetic-theory calculations based on the Boltzmann equation, highlighting how the QMC data can guide improvements in the accuracy of the collision integral.
Keywords: Graphene; Conductivity; Strongly correlated electrons; Boltzmann equation; Quantum Monte Carlo
