SKM 2021 – scientific programme

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MA: Fachverband Magnetismus

MA 18: Posters Magnetism V

MA 18.20: Poster

Friday, October 1, 2021, 10:00–13:00, P

Time-Resolved Imaging of Ferromagnetic Resonances in the Oldenburg Ultrafast Transmission Electron Microscope (UTEM) — •Jonathan Weber, Nikita Porwal, Michael Winkelhofer, and Sascha Schäfer — Carl-von-Ossietzky Universität Oldenburg, Deutschland

Recent progress in the development of laser driven, high-brightness photocathodes offers a path to investigate magnetization dynamics with unparalleled resolution by employing a Lorentz imaging scheme in an ultrafast transmission electron microscope [1,2].

Aiming to extend the accessible frequency range, we develop a setup for Lorentz-imaging detected ferromagnetic resonances. Beyond the nanometer spatial resolution, inherent to transmission electron microscopy, a setup for fs-temporal resolution is presented, employing nano-localized photoemission from a Schottky-field emitter in the Oldenburg UTEM. The laser system which is used for the generation of ultrashort electron pulses is also utilized as a master clock for the synthetization of phase-locked microwave signals [3]. Making use of a custom-made sample holder we pass these signals to a microresonator which excites precessions of the magnetic moments in nanostructured Py films at GHz frequencies. With this advanced excitation scheme we aim to further establish ultrafast Lorentz microscopy as a powerful tool to characterize magnetic dynamics on the nanoscale.

[1] T. Eggebrecht et al. Phys. Rev. Lett. 118, 097203 (2017)

[2] N. R. da Silva et al. Phys. Rev. X 8, 031052 (2018)

[3] M.R. Otto et al. Struct. Dyn. 4, 051101 (2017)