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MA: Fachverband Magnetismus

MA 11: Posters Magnetism III

MA 11.9: Poster

Wednesday, September 29, 2021, 13:30–16:30, P

Parametric pumping in out-of-plane magnetized ferrite films towards magnon Bose-Einstein condensation — •Andra Pirktina, Timo B. Noack, Vitaliy I. Vasyuchka, Alexander Serga, and Burkard Hillebrands — Fachbereich Physik and Landesforschungszentrum OPTIMAS, Technische Universität Kaiserslautern, 67663 Kaiserslautern, Germany

The Bose–Einstein condensate (BEC) in a parametrically overpopulated gas of spin-wave quanta—magnons—manifests itself as a spontaneous formation of a coherent spin wave state at the energy minimum of the magnon spectrum. Magnon BECs, which are observed at gigahertz frequencies in tangentially magnetized yttrium iron garnet (YIG) films even at room temperature, can be used as signal sources for microwave applications and as information carriers in wave and quantum computing. However, due to the wavelength of the order of a few micrometers, the magnon BEC is detected mainly by the Brillouin light scattering spectroscopy, which is hardly applicable to real devices.

Here, we report on the spontaneous BEC formation in the out-of-plane magnetization geometry, where the magnon spectrum has a minimum at zero wavenumber, and the BEC frequency coincides with the ferromagnetic resonance frequency. In this case, the BEC was detected as a microwave electromagnetic signal by an inductive microstrip antenna. A small signal line width of 1.4 MHz was measured after the pump power exceeded the parametric instability threshold by 34 dB. =-1

Funded by the ERC Advanced Grant 694709 SuperMagnonics and by the DFG within TRR 173 – 268565370 (project B04).