Berlin 2024 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 20: Poster I

MA 20.16: Poster

Dienstag, 19. März 2024, 16:30–19:00, Poster A

Impact of a lateral gradient in the ferromagnet thickness on the ultrafast response of a spintronic THz emitter — •Paul Alexander Marschall¹, Wolfgang Hoppe¹, Oliver Gückstock², Tobias Kampfrath², and Georg Woltersdorf¹ — ¹Martin Luther University Halle-Wittenberg, Institute of Physics, Halle (Saale), Germany — ²Freie Universität Berlin, Physics, Berlin, Germany

Illuminating a nanometer thin metallic bilayer consisting of a ferromagnetic (FM) and a non-magnetic layer (NM) with an intense femtosecond laser pulse launches an ultrafast spin current from the FM into the NM and is subsequently converted into a charge current in the NM. This system is established as a so called spintronic terahertz emitter usable either as source for THz radiation [1] or for on-chip ultrafast current pulses [2]. By applying an external magnetic field the polarity of radiation or current can be fully inverted. Introducing a lateral gradient in the FM thickness leads to a significant ultrafast response which is not switchable by an external magnetic field and depends on the FM thickness. In this study the origin of this signal is systematically investigated.

[1] T. Seifert et al. Efficient metallic spintronic emitters of ultrabroadband terahertz radiation. Nature Photon 10, 483-488 (2016)

[2] W. Hoppe et al., On-chip generation of ultrafast current pulses by nanolayered spintornic terahertz emitters. ACS Applied Nano Materials 4 (7), 7454-7460 (2021)

Keywords: Spin-Hall Effect; Ultrafast current pulses; Thickness gradient; Material dependence