Dresden 2020 – wissenschaftliches Programm

Die DPG-Frühjahrstagung in Dresden musste abgesagt werden! Lesen Sie mehr ...

Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

O: Fachverband Oberflächenphysik

O 27: Poster Session - Graphene: Electronic Structure, Excitations, etc.

O 27.1: Poster

Montag, 16. März 2020, 18:15–20:00, P1A

Anisotropic Carrier Dynamics in HOPG — •Hauke Beyer, Tim Jacobsen, Gerald Rohde, Kai Rossnagel, and Michael Bauer — Institute of Experimental and Applied Physics, Kiel University, 24098 Kiel, Germany

Time- and angle-resolved photoelectron spectroscopy is employed to study the decay of an anisotropic momentum distribution generated in the Dirac-cone of HOPG upon excitation with linearly polarized light. At the primary excitation energy the transient population within the probed momentum cut shows distinct delays of up to ∼ 10 fs for indirect excitations in comparison to the direct photoexcitation channel. The observed delay times are associated with momentum isotropization processes and show a good qualitative agreement with calculations based on a model introduced in Ref. [1]. As excited carriers are redistributed towards the Dirac-point via electron-electron and electron-phonon scattering we furthermore observe that the momentum anisotropy gets gradually weaker. In contrast to previous quasistatic studies [2, 3], our results allow also capturing the temporal evolution of momentum redistribution processes driven by fundamental interactions in graphitic materials.

[1] E. Malic et al., Phys. Rev. B 84, 205406 (2011).

[2] S. Aeschlimann et al., Phys. Rev. B 96, 020301(R) (2017).

[3] M. Mittendorff et al., Nano Letters 12, 1504 (2014).