Regensburg 2022 – scientific programme

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MA: Fachverband Magnetismus

MA 19: Poster 1

MA 19.29: Poster

Tuesday, September 6, 2022, 17:30–20:00, P2

Ultrafast Lorentz microscopy with magnetic field excitation at microwave frequencies — Jonathan Tilman Weber, Nikita Porwal, •Andreas Wendeln, Michael Winklhofer, 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 high spatial and temporal resolution, utilizing a Lorentz imaging approach in ultrafast transmission electron microscopy (UTEM) [1]. In particular, non-optical excitation schemes, such as current or field excitation provide pathways for a selective triggering of magnetic dynamics. Extending the available frequencies in such experiments [2], we developed a TEM sample holder based on a two-dimensional microwave cavity, with which we can excite ferromagnetic resonances in magnetic nanostructures. The microwave excitation signals are phase-locked to the nanolocalized photoemission of ultrashort electron pulses from a Schottky field emitter, using high harmonics of the amplified laser system as a master clock for their synthetization [3]. With this advanced excitation and measurement scheme we aim to image ferromagnetic resonance modes with high spatial and temporal resolution and to further establish ultrafast Lorentz microscopy as a powerful tool to characterize magnetization dynamics on the nanoscale.

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

[2] M. Möller et al. Commun Phys 3, 36 (2020).

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