Regensburg 2022 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 33: Poster Tuesday: Ultrafast Processes 2

O 33.1: Poster

Dienstag, 6. September 2022, 11:00–13:00, P3

Anisotropic carrier dynamics in single crystalline graphite — •Hauke Beyer, Petra Hein, Kai Rossnagel, and Michael Bauer — Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, Germany

Time- and angle-resolved photoelectron spectroscopy at 35 fs time-resolution is employed to study the carrier dynamics in the Dirac cone of graphite upon excitation with linearly polarized light. Due to the pseudo spin degree of freedom, the nascent photogenerated carrier distribution exhibits a strong anisotropy in momentum space. We observe the formation of a quasi-thermalized distribution on ultrafast timescales (∼ 10 fs) through e-e interactions exhibiting a clear azimuthal anisotropy similar to findings for graphene [1]. For the azimuthal thermalization our data reveal a characteristic time scale of 40 ± 10 fs. The residual non thermal part of the electron distribution shows a time-dependent shift in energy by ∼ 150 meV, which we assign to the formation of a steplike distribution due to e-ph interactions. The results are in good qualitative agreement with calculations based on a model introduced in Ref. [2].

[1] S. Aeschlimann et al., Phys. Rev. B 96, 020301(R) (2017).
[2] E. Malic et al., Phys. Rev. B 84, 205406 (2011).