Regensburg 2025 – scientific programme

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MA: Fachverband Magnetismus

MA 48: Ultrafast Magnetization Effects II

MA 48.7: Talk

Friday, March 21, 2025, 12:45–13:00, H20

On-Chip Multilayer Spintronic THz Emitters — •Wolfgang Hoppe¹, Amine Wahada², Stuart Parkin³, and Georg Woltersdorf¹ — ¹Institute of Physics, Martin-Luther-Universität Halle-Wittenberg, Von-Danckelmann-Platz 3, 06120 Halle, Germany — ²Department of Physical Chemistry, Fritz Haber Institute, Faradayweg 4-6, 14195 Berlin, Germany — ³Max Planck Institute for Microstructured Physics, Weinberg 2, 06120 Halle, Germany

Nanometer thin ferromagnet/heavy metal bilayers illuminated by intense short laser pulses have proven to be a realiable source for THz emission [1]. When integrated into a gold waveguide structure, the bilayer can be used as an on-chip source for ultrafast current pulses from the GHz to the THz regime [2]. Stacking severeral bilayers, each separated by a thin MgO interlayer enhances the charge current amplitude, as the MgO suppresses spin-currents in between the individual bilayers [3]. In this way we construct multilayers where all charge currents add up constructively, enhancing the signal up to a factor of three. As one possible application these ultrafast currents could be used to switch the magnetization of an adjacent ferromagnet, similar to previous experiments [4]. Electro-optic sampling is employed to characterize the charge current with sub-ps time resolution.
References:
[1] Seifert et al., Nat. Photonics 10 (2016) 438-488
[2] W. Hoppe et al., ACS. Appl. Nano Mater. 4,7 (2021) 7454-7460
[3] A. Wahada et al., ACS Nano Lett. 22, 9 (2022) 3539-3544
[4] Y. Yang et al., Sci. Adv. 3, 11 (2017) e1603117

Keywords: Ultrafast demagnetization; ISHE; On-chip; THz current pulses; Microstructured waveguides