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O: Fachverband Oberflächenphysik
O 40: Ultrafast electron dynamics at surface and interfaces – Poster (joint session O/TT)
O 40.12: Poster
Tuesday, March 10, 2026, 14:00–16:00, P2
Ultrafast STEM locked to GHz sample excitation — •Andreas Wendeln1, Alexander Schröder1, Sakal Singla1, and Sascha Schäfer1,2 — 1Department of Physics, University of Regensburg, Regensburg, Germany — 2Regensburg Center for Ultrafast Nanoscopy (RUN), Regensburg, Germany
Ultrafast transmission electron microscopy (UTEM) has been an established method for investigating nanoscale dynamics for several years, combining the nanometer spatial resolution of TEM with the femtosecond temporal resolution of a pump-probe approach. In recent years, there have been numerous advances in the development of new femtosecond electron sources, such as laser-driven Schottky [1] or cold-field emitters [2]. A combination of these sources with advanced electron optical elements, such as a probe aberration corrector, is expected to deliver even smaller electron spot sizes and to increase the available pulsed current but was not yet demonstrated. Here, we present a measurement scheme for ultrafast STEM with a focus on magnetic imaging, utilizing an aberration corrector and a laser-driven cold-field emitter. In initial measurements using a continuous photoelectron beam, the measurement method is characterized regarding experimental parameters, such as probe currents, focal spot sizes, and stability. Subsequently, we report the locking of femtosecond electron pulse train at repetition rates between 100 kHz up to 80 MHz to GHz radiofrequency currents which we aim to employ for DPC and ptychography imaging schemes of current-driven magnetic dynamics. [1] Feist et al., Ultramicroscopy, 2017. [2] Schröder et al., Ultramicroscopy, 2025.
Keywords: UTEM; STEM; pulsed electron sources; laser-driven cold-field emitte; aberration corrector