Dresden 2017 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 75: Ultrafast Electron and Spin Dynamics

O 75.7: Vortrag

Mittwoch, 22. März 2017, 16:30–16:45, TRE Phy

Resolving initial stages of carrier thermalization in graphite using time-resolved ARPES with sub-15 fs temporal and near Fourier-limited spectral resolution — •Gerald Rohde¹, Ankatrin Stange¹, Arne Müller¹, Marcel Behrendt¹, Kerstin Hanff¹, Lars-Philip Oloff¹, Lexian Yang², Petra Hein¹, Kai Rossnagel¹, and Michael Bauer¹ — ¹Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, Germany — ²Department of Physics, Tsinghua University, Beijing, People’s Republic of China

Carrier dynamics in graphitic materials have been subject of theoretical and experimental investigations in recent years. State-of-the-art experimental approaches address the time scales of excitation and relaxation of hot carrier distributions, aiming to break their evolutions down into the underlying fundamental scattering processes as ultimately governed by electron-electron and electron-phonon interaction. Using time- and angle-resolved photoelectron spectroscopy with sub-15 fs temporal and near Fourier-limited spectral resolution, we report here on the build-up of an out-of-equilibrium electron distribution in graphite within 13 fs and its further evolution during the thermalization towards a Fermi-Dirac distribution. We discuss potential processes causing this transition and compare the results to corresponding data reported for graphene [1]. Moreover, indications for a momentum redistribution of the hot carriers on ultrafast time scales are presented following a momentum-selective photoexcitation.
[1] I. Gierz et al., Phys. Rev. Lett. 115, 086803 (2015).