Dresden 2020 – scientific programme
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MA: Fachverband Magnetismus
MA 30: Ultrafast Magnetization III
MA 30.3: Talk
Wednesday, March 18, 2020, 10:00–10:15, HSZ 101
Separating spin and orbital magnetic dynamics via time-resolved x-ray absorption — •N. Thielemann-Kühn1, T. Amrhein1, W. Bronsch1, S. Jana2, N. Pontius2, C. Schüßler-Langeheine2, R. Engel3, P. Miedema3, M. Beye3, B. van Kuiken4, A. Scherz4, R. Carley4, L. Le Guyader4, N. Agarwal4, L. Mercadier4, G. Mercurio4, M. Teichmann4, A. Yaroslavtsev4, and M. Weinelt1 — 1Freie Universität Berlin, Arnimallee 14, 14195 Berlin — 2Helmholtz-Zentrum Berlin für Materialien und Energie, Alberteinsteinstr. 15, 12489 Berlin — 3Deutsches Elektronen Synchrotron DESY, Notkestraße 85, 22607 Hamburg — 4European XFEL GmbH, Holzkoppel 4, 22869 Schenefeld
We study ultrafast spin and orbital momenta dynamics by recording highly energy-resolved 3d-4f absorption spectra. After optical excitation we identify changes in L and S via the multiplet structure. Due to the strong localization of the 4f states the absorption spectra of rare earth metals can be described by atomic calculation of their trivalent ions. At the European XFEL we preformed pump-probe X-ray absorption spectroscopy for the RE-metals Tb and Gd, at the 3d-4f absorption edge. We find that only for Tb we excite multiplet components with the pump laser. This implies transient decoupling of L and S, for which we observe a time-dependence that follows the 5d6s hot electron distribution. We conclude that scattering with the optically excited 5d6s valence electrons leads to excitation of the 4f multiplet components.