Dresden 2020 – scientific programme

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MA: Fachverband Magnetismus

MA 63: Spin: Transport, Orbitronics and Hall Effects III

MA 63.5: Talk

Friday, March 20, 2020, 10:30–10:45, HSZ 403

Fast screening of THz current pulses in heavy metal/ferromagnet bilayers — •Wolfgang Hoppe¹, Rouven Dreyer¹, Liane Brandt¹, Tobias Kampfrath², Mazhar Nawaz Ali³, and Georg Woltersdorf¹ — ¹Martin Luther University Halle-Wittenberg, Physics, Halle, Germany — ²Freie Universität Berlin, Physics, Berlin, Germany — ³Max-Planck Institute of Microstructure Physics, Halle, Germany

We use femtosecond optical pump pulses to generate ultrashort current pulses in heavy metal/ferromagnet bilayers. The optical excitation from an ultrafast amplified laser system injects ultrashort spin current pulses from the ferromagnet into the heavy metal layer via the spin-dependent Seebeck effect [1]. Subsequently, this spin current pulse is converted into a charge current pulse inside the heavy metal layer via the inverse spin-Hall effect (ISHE) [2]. To investigate these ultrafast current pulses there are two different approaches available. Quantitatively, the exact waveform can be measured using electrooptic sampling. Qualitatively, a probing tip connected to a 50 GHz sampling oscilloscope yields a quick method to characterize the ISHE in plain films and microstructured devices. This fast approach can be utilized to investigate the signal dependence on varying layer thicknesses, different layer materials and wedged interlayers between the heavy metal and ferromagnetic layer.

[1] A. Melnikov et. al.: doi: 10.1103/PhysRevLett.119.017202

[2] T. Seifert et. al.: doi:10.1038/nphoton.2016.91