SKM 2023 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 16: Ultrafast Electron Dynamics at Surface and Interfaces II

O 16.4: Topical Talk

Montag, 27. März 2023, 15:45–16:15, TRE Phy

Microscopic insight into non-equilibrium dynamics through time-resolved x-ray absorption spectroscopy — •Andrea Eschenlohr — Faculty of Physics and CENIDE, University Duisburg-Essen, Lotharstr. 1, 47057 Duisburg, Germany

Time-resolved x-ray absorption spectroscopy provides access to element- and chemically sensitive information on the femto- to picosecond timescales of the elementary microscopic processes involving charge, spin and lattice dynamics in solids via optical pump, x-ray probe experiments. Recently implemented specialized x-ray optics at the SCS instrument of European XFEL allow for a simultaneous acquisition of the ground state and optically excited x-ray spectra as well as a reference signal for normalization of the data to the incident x-ray intensity, and thus provide excellent data quality in combination with kHz repetition rates [1]. We employ this scheme to analyze the temporal evolution of the electronic structure of ferromagnetic Ni after optical excitation and distinguish transient broadening and energy shifts in the absorption spectra, which we show to be caused by electron repopulation and correlation-induced modifications of the electronic structure, respectively. Crucially, an ab initio theoretical description requires taking the local Coulomb interaction into account, revealing the temporal interplay between electron correlations and ultrafast spin-dependent charge dynamics [2].

[1] L. Le Guyader et al., arxiv.org/abs/2211.04265

[2] T. Lojewski et al., arxiv.org/abs/2210.13162