Regensburg 2022 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 35: Poster 2

MA 35.10: Poster

Donnerstag, 8. September 2022, 16:00–18:00, P4

Magnon Bose–Einstein condensates in microscopic thermal landscapes — •Franziska Kühn, Matthias R. Schweizer, Georg von Freymann, Alexander A. Serga, and Burkard Hillebrands — Fachbereich Physik and Landesforschungszentrum OPTIMAS, TU Kaiserslautern, Kaiserslautern, Germany

This contribution is focused on the behavior of a magnon Bose–Einstein condensate (BEC) in artificial magnetization landscapes at the scale of the wavelengths of condensed magnons. In our work, the magnon condensate is created by overpopulation of a magnon gas using microwave parametric pumping. By combining a heating laser with a microscopic phase-based wave front modulation technique, a temperature pattern is imprinted on the yttrium-iron-garnet film sample. Accordingly, the saturation magnetization, on which the dispersion relation of the magnons depends, is shifted. The corresponding spatial variation of the condensate frequency, acting as an artificial potential for the BEC, affects its dynamics and propels magnon supercurrents and Bogoliubov waves. Since the size of these patterns is small compared to the area of BEC formation, it is possible to investigate the BEC in two-dimensional thermal landscapes. In the experiment, by utilizing microfocused Brillouin light scattering spectroscopy, we study the anisotropy of the two-dimensional density distribution of a magnon BEC and the possibility of interference effects between Bogoliubov waves.

Funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) – TRR 173 – 268565370 (project B04).