Regensburg 2019 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 97: Ultrafast Electron Dynamics at Surfaces and Interfaces III

O 97.10: Vortrag

Freitag, 5. April 2019, 12:45–13:00, H16

Local and Non-Local Relaxation Dynamics of Hot Electrons in Au/Fe/MgO(001) — •Yasin Beyazit¹, Jan Beckord¹, John Thomas¹, Ping Zhou¹, Detlef Diesing², Manuel Ligges¹, and Uwe Bovensiepen¹ — ¹Faculty of Physics, University of Duisburg-Essen, 47048 Duisburg, Germany — ²Faculty of Chemistry, University of Duisburg-Essen, 45141 Essen, Germany

Photo-excited, hot electrons in multilayer thin films exhibit local and non-local dynamics which lead to relaxation and transport effects. The investigation of their interplay is so far mainly based on all-optical measurements. We present a novel tool for energy-resolved analysis of local and non-local relaxation dynamics in condensed matter. By using a back-pump/front-probe experimental configuration in femtosecond time-resolved, two-photon photoemission (tr-2PPE), we aim at separating these relaxation processes. The tr-2PPE intensity provides the relaxation time τ and the delay of the maximum intensity t^*, and, thus, independent observables which we discuss in terms of inelastic relaxation and ballistic transport. We show first results for Au/Fe/MgO(001) and (i) τ as a function of energy E−E_F as well as Au thickness d_Au and (ii) t^* regarding energy-resolved transport velocities of hot electrons. The proportionality between t^* and Au thickness points strongly towards ballistic transport. Our obtained velocities are in a good agreement with the literature values. This study was funded by the DFG through SFB1242.