Regensburg 2025 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 20: Magnonics II

MA 20.1: Vortrag

Mittwoch, 19. März 2025, 09:30–09:45, H16

Wavenumber-dependent magnetic losses in YIG-GGG heterostructures at millikelvin temperatures — •David Schmoll¹, Andrey A. Voronov¹, Rostyslav O. Serha¹, Denys Slobodianiuk², Khrystyna Levchenko¹, Claas Abert¹, Sebastian Knauer¹, Dieter Suess¹, Roman Verba², and Andrii V. Chumak¹ — ¹University of Vienna, Vienna, Austria — ²V.G. Baryakhtar Institute of Magnetism of the NAS of Ukraine, Kyiv, Ukraine

With its low magnetic damping, the ferrimagnet yttrium iron garnet (YIG), grown on gadolinium gallium garnet (GGG), is the most promising material for magnon based quantum technologies, wich demand long decoherence times. While such samples are already well established at room temperature, further knowledge needs to be acquired at millikelvin temperatures, due to the paramagnetic character of the GGG substrate. We report on propagating spin-wave spectroscopy studies at temperatures between 4 K to 26 mK and the recorded change of the dissipation rate. Additionally, we compute the dispersion and the dissipation rate of the layered YIG-GGG magnetic system quasi- analytically and with micromagnetic simulations, allowing us to investigate the magnon losses with respect to wavenumber. Contrary to room temperature, we observe a significant increase of the magnetic losses with k at cryogenic temperatures, introduced by the dipolar coupling between the ferrimagnetic YIG film and the partially magnetized GGG substrate. Our theoretical calculations predict a steady decrease of the dissipation for short-wavelength exchange magnons.

Keywords: Magnons; Millikelvin; Magnetic losses; Wavenumber; Paramagnet