SurfaceScience21 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 67: Poster Session V: Ultrafast electron dynamics at surface and interfaces I

O 67.7: Poster

Mittwoch, 3. März 2021, 10:30–12:30, P

Relaxation and Transport Processes of Hot Electrons in Au/Fe/MgO(001) — •Yasin Beyazit¹, Ping Zhou¹, Florian Kühne^1,2, Jan Philipp Meyburg², Detlef Diesing², and Uwe Bovensiepen¹ — ¹Faculty of Physics, University Duisburg-Essen — ²Faculty of Chemistry, University Duisburg-Essen, Germany

This work presents an energy resolved analysis of relaxation and transport processes of excited electrons in the time domain. By employing femtosecond laser pulses with 2 eV pump energy and pulse width less than 35 fs we excite hot electrons in epitaxially grown Au/Fe/MgO(001). The photo-excited electrons exhibit local and nonlocal dynamics which lead to relaxation and transport processes of charge carriers. We perform time-resolved two photon photoelectron spectroscopy (tr-2PPE) with a particular excitation scheme; back side pumping and front side probing. The hot electrons are excited in the buried Fe layer 2 eV above the Fermi level E_F and experience subsequently spatiotemporal transport through the Fe-Au interface towards the Au surface and local inelastic relaxation. By analysis of the relaxation dynamics as a function of Au film thickness we determine the electron lifetimes of bulk Au and Fe and distinguish the relaxation in the heterostructures constituents. Furthermore, we show that the hot electrons propagate through the Au in a superdiffusive regime [1]. Additional measurements allow us to discuss contributions of secondary electrons. This study was funded by the DFG through SFB 1242. [1] Beyazit et al., PRL 125, 076803 (2020)