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MA: Fachverband Magnetismus

MA 46: Poster II

MA 46.57: Poster

Donnerstag, 21. März 2024, 15:00–18:00, Poster C

The signature of 4f multiplet excitations to the M₅/M₄ branching ratio in Terbium and their influence on magnetization dynamics — •Beyza Salantur¹, Tim Amrhein¹, Niko Pontius², Christian Schuessler-Langeheine², Martin Weinelt¹, and Nele Thielemann-Kuehn¹ — ¹Freie Universität Berlin, Fachbereich Physik, Arnimallee 14, 14195 Berlin, Germany — ²Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Albert-Einstein-Str. 15, 12489 Berlin, Germany

In 4f-rare earth metals, magnetic order is established by intra- and interatomic exchange between 4f and 5d spins. We show that upon ultrafast optical excitation of the 5d electrons inelastic 5d-4f electron-electron scattering can alter the 4f orbital state and therewith the total angular momentum J [1]. This directly affects magneto crystalline anisotropy and has important implications for magnetization dynamics. Within a time-resolved X-ray absorption study at the FemtoSpeX slicing facility of BESSY II (HZB) we found transient changes of the M₅/M₄ branching ratio in Terbium, indicative of multiplet excitations changing J [2].

[1] N. Thielemann-Kühn et al., Optical control of 4f orbital state in rare-earth metals. https://doi.org/10.48550/arXiv.2106.09999 (Sci- ence Advances, in revision)

[2] B. T. Thole and G. van der Laan., Branching ratio in x-ray absorption spectroscopy. Phys. Rev. B, 38:3158-3171, Aug 1988.

Keywords: rare earths; ultrafast; x-ray absorption; inelastic 5d-4f electronic scattering