Regensburg 2022 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 2: Ultrafast Electron Dynamics at Surfaces and Interfaces 1
O 2.9: Vortrag
Montag, 5. September 2022, 12:30–12:45, H3
Far-from-equilibrium electron-phonon interactions in optically-excited graphene — •Marco Merboldt1, Marten Düvel1, Jan Philipp Bange1, Michael Stellbrink1, Hannah Strauch1, Klaus Pierz2, Hans Werner Schumacher2, Davood Momeni2, Daniel Steil1, G. S. Matthijs Jansen1, Sabine Steil1, Dino Novko3, Stefan Mathias1, and Marcel Reutzel1 — 1I. Physikalisches Institut, Georg-August-Universität Göttingen, Göttingen, Germany — 2Physikalisch-Technische Bundesanstalt, Braunschweig, Germany — 3Institute of Physics, Zagreb, Croatia
Comprehending far-from-equilibrium many-body interactions is one major goal of current ultrafast condensed matter physics research. A particularly interesting but barely understood situation occurs during strong optical excitation, where electron and phonon systems are significantly perturbed from their equilibrium and cannot be described by Fermi-Dirac or Bose-Einstein distributions, respectively.
Here, we use time- and angle-resolved photoelectron spectroscopy (trARPES) to study such situation for the prototypical material graphene. We show that upon optical excitation, it exhibits a complex non-equilibrium many-body response by evaluating the Dirac state linewidth and thus the imaginary part of the quasiparticle self-energy ImΣ from spectrally deconvoluted trARPES data. By employing first-principles theoretical modeling, we find that the observed experimental features are caused by ultrafast NEQ scatterings between optical phonons and photoexcited charge carriers, active on timescales well below 100 fs. Düvel, Merboldt et al., Nano Letters, accepted.