SKM 2021 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 8: INNOMAG e.V. Dissertationspreis / Ph.D. Thesis Prize (2020)

MA 8.3: Vortrag

Mittwoch, 29. September 2021, 10:50–11:15, H2

Spintronics with Terahertz Radiation: Probing and driving spins at highest frequencies — •Tom Sebastian Seifert — Freie Universität Berlin, Berlin, Germany

Spin-orbit interaction (SOI) will be of central importance for future spin-based electronics (spintronics) as it permits, for example, the conversion of charge into spin currents and vice versa via the spin Hall effect. It is highly interesting to study spin dynamics at terahertz (THz) frequencies because spintronic devices should eventually operate at THz rates. In our experiments, we employ femtosecond optical and THz pulses to trigger ultrafast spin and charge dynamics in magnetic thin-film stacks featuring a strong SOI. In particular, we study THz emission from multilayers consisting of magnetic and a nonmagnetic materials [1,2,3]. By varying the magnetic layer material, we aim at identifying the different mechanisms that can lead to the ultrafast generation of spin currents. Such mechanisms include spin-voltage-driven transport [4] by conduction-band electrons in metal-metal stacks and magnon-mediated transfer of spin angular momentum in insulator-metal stacks [5]. Finally, we turn from probing to driving spins at highest speeds by demonstrating the picosecond writing speed of an antiferromagnetic memory element based on CuMnAs employing strong THz pulses[6]. References: [1] T. Seifert et al., Nat. Phot. 10 (2016). [2] T. Kampfrath et al., Nat. Nanotech. 8 (2013). [3] T. Seifert et al., APL, 110, 252402 (2017). [4] R. Rouzegar et al., ArXiv 2103.11710 (2021) [5] T. Seifert et al., Nat. Commun. 9 (2018). [6] K. Olejnik et al., Science Adv. 4 (2018).