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MA: Fachverband Magnetismus
MA 8: INNOMAG e.V. Prizes 2024 (Diplom-/Master and Ph.D. Thesis)
MA 8.2: Talk
Monday, March 18, 2024, 15:20–15:40, H 1058
Dynamics of magnon gases in microscopic temperature landscapes — •Franziska Kühn1, Matthias R. Schweizer1, Georg von Freymann1,2, Alexander A. Serga1, and Burkard Hillebrands1 — 1Fachbereich Physik and Landesforschungszentrum OPTIMAS, RPTU Kaiserslautern-Landau, 67663 Kaiserslautern, Germany — 2Fraunhofer Institute for Industrial Mathematics ITWM, Fraunhofer Platz 1, 67663 Kaiserslautern, Germany
This work is focused on the behavior of a thermally generated magnon gas in artificial magnetization landscapes on the micrometer scale. A unique setup was created by combining microfocused Brillouin light scattering spectroscopy with a heating laser, which imprints two-dimensional temperature landscapes onto the yttrium-iron garnet film sample by phase-based wavefront modulation. The temperature change, regulated by the power of the optical intensity patterns, influences the saturation magnetization and shifts the magnon dispersion relation. It was demonstrated with both measurements and simulations, that in addition to the magnetization variations, it is necessary to consider the connected variations of the demagnetization field. The local temperature-dependent demagnetization field influences the dispersion relation in the opposite direction and affects different magnon modes diversely, leading to strong frequency shifts. This effect creates a powerful tool for the manipulation of magnon Bose-Einstein condensates as well as for the directional control of magnon supercurrents. Funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation)-TRR 173/2-268565370 Spin+X (Project B04)
Keywords: magnon gas temperature landscapes; demagnetization field; Brillouin light scattering spectroscopy; temperature landscapes