Berlin 2018 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 21: Poster I
MA 21.45: Poster
Dienstag, 13. März 2018, 09:30–13:00, Poster A
Launching magnons at the terahertz speed of the spin Seebeck effect — Tom Seifert1,2, Joel Cramer3, Joe Barker4, Samridh Jaiswal3, Gerhard Jakob3, Martin Wolf2, Georg Woltersdorf5, Piet W. Brouwer1, Mathias Kläui3, and •Tobias Kampfrath1,2 — 1FU Berlin — 2FHI Berlin — 3JGU Mainz — 4Tohoku University, Japan — 5MLU Halle
We study the initial steps of the spin Seebeck effect with 10 fs time resolution in prototypical bilayers of the ferrimagnet yttrium iron garnet and platinum. Following excitation of the metal with an ultrashort laser pulse, the spin Seebeck current js is measured all-optically using the inverse spin Hall effect and terahertz electrooptic sampling. The current rises on the ∼ 200 fs time scale on which the electrons in the metal approach a Fermi-Dirac distribution. This observation is a hallmark of the assumption that the spin transfer arises from conduction electrons scattering off the magnetic interface. Model-supported analysis shows that js follows the dynamics of the metal electrons quasi-instantaneously because their spins have a correlation time of only ∼ 4 fs and deflect the ferrimagnetic moments without inertia. Promising applications for material characterization, interface probing, spin-noise detection and terahertz spin pumping come into reach.