Dresden 2020 – scientific programme

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O: Fachverband Oberflächenphysik

O 8: Ultrafast Electron Dynamics I: Surfaces and Interfaces (joint session O/MA)

O 8.7: Talk

Monday, March 16, 2020, 12:00–12:15, TRE Phy

Carrier dynamics in a laser-excited Fe/(MgO)(001) heterostructure from real-time TDDFT — •Elaheh Shomali, Markus Ernst Gruner, and Rossitza Pentcheva — Department of Physics and Center for Nanointegration, CENIDE, University of Duisburg-Essen, Germany

The interaction of a femtosecond optical pulse with a metal/oxide interface has been addressed based on time-dependent density functional theory (TDDFT) in the real-time domain using the Elk code. We systematically studied electronic excitations of a Fe₁/(MgO)₃(001) heterostructure as a function of laser frequency, peak power density and polarization direction. We find a marked anisotropy in the response to in-plane and out-of-plane polarized light, which changes its character for frequencies lower and higher than the MgO band gap. For laser frequencies between the MgO band gap and the charge transfer gap, interface states resulting from the hybridization of the d_3z²−r² orbitals of Fe and the p_z orbitals of O at the interface may foster the propagation of excitations into the central layer of MgO. Spin-orbit coupling (SOC) is found to result in a small time-dependent reduction of magnetization only. Finally, we extend our investigation to thicker heterostructures, such as Fe₃/(MgO)₅(001).

Financial support from the DFG within SFB 1242 (project C02) is gratefully acknowledged.