Berlin 2024 – scientific programme
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MA: Fachverband Magnetismus
MA 20: Poster I
MA 20.19: Poster
Tuesday, March 19, 2024, 16:30–19:00, Poster A
THz spin and charge currents in a non-centrosymmetric ferromagnet — Junwei Tong1, Zdenek Kaspar1, Afnan Alostaz1,5, Bruno Serrano1, Xianmin Zhang2, Genaro Bierhance1,4, F. Gerhard3, Johannes Kleinlein3, Tobias Kießling3, Charles Gould3, Laurens Molenkamp3, Tom Seifert1, and •Tobias Kampfrath1,4 — 1Freie Universität Berlin, Germany — 2Northeastern University, China — 3Physikalisches Institut der Universität Würzburg (EP3), and Institute for Topological Insulators, Am Hubland, Germany — 4Fritz Haber Institute of the Max Planck Society, Germany — 5Jülich Research Center, Germany
Investigating spin-to-charge conversion (SCC) on ultrafast time scales is important for understanding its physical mechanisms and the development of terahertz (THz) sources. SCC may arise from, e.g., the inverse spin Hall effect and spin-galvanic effect, whose experimental separation is challenging. Here, we use a femtosecond laser pulse to excite thin films of the ferromagnetic Heusler compound NiMnSb and measure the emitted THz electromagnetic pulse. We observe THz signals and, thus, ultrafast photocurrents that can be ascribed to SCC by contributions with Rashba- and Dresselhaus-like symmetry. Based on a symmetry analysis, we separate both contributions and find that the related photocurrents exhibit different temporal dynamics. Further, by changing the magnetic field, we observe that the Rashba-like current is mainly induced by ordinary Hall effect, whereas the Dresselhaus-like current is independent of the magnetic field strength. We discuss possible microscopic scenarios of the Dresselhaus-like contribution.
Keywords: Spin-to-charge conversion; Terahertz; Dresselhaus effect; Rashba effect