Local and non-local electron dynamics of Au/Fe/MgO(001) heterostructures analyzed by time-resolved two-photon photoemission spectroscopy

Abstract

Employing femtosecond laser pulses in front and back side pumping of Au/Fe/MgO(001) combined with detection in two-photon photoelectron emission spectroscopy we analyze local relaxation dynamics of excited electrons in buried Fe, injection into Au across the Fe-Au interface, and electron transport across the Au layer at 0.6 to 2.0 eV above the Fermi energy. By analysis as a function of Au film thickness we obtain the electron lifetimes of bulk Au and Fe and distinguish the relaxation in the heterostructure's constituents. We also show that the excited electrons propagate through Au in a superdiffusive regime and conclude further that electron injection across the epitaxial interface proceeds ballistically by electron wavepacket propagation.

arXiv comment5 pages, 4 figures

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Cited by in corpus (8)

• Time- and Angle-Resolved Photoemission Studies of Quantum Materials
• Theoretical description of optical and X-ray absorption spectra of MgO including many-body effects
• Implementation of the electronic non-equilibrium in the two-temperature model
• Ultrafast transport and energy relaxation of hot electrons in Au/Fe/MgO(001) heterostructures analyzed by linear time-resolved photoelectron spectroscopy
• Spatio-Temporal Electron Propagation Dynamics in Au/Fe/MgO(001) in nonequilibrium: Revealing Single Scattering Events and the Ballistic Limit
• Ultrafast electron dynamics in Au/Fe/MgO(001) analyzed by Au- and Fe-selective pumping in time-resolved two-photon photoemission spectroscopy: Separation of excitations in adjacent metallic layers
• Anisotropic carrier dynamics in a laser-excited Fe${}_1$/(MgO)${}_3$(001) heterostructure from real-time time-dependent DFT
• Control of ultrashort spin current pulses in metallic multilayers