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MA: Fachverband Magnetismus

MA 52: Poster Magnetism III

MA 52.9: Poster

Thursday, March 12, 2026, 15:00–17:00, P4

Active noise spectroscopy of magnon-photon polaritons — •Lars Nikolas Heß, Philipp Schwenke, Vitaliy Vasyuchka, Kevin Künstle, and Mathias Weiler — Fachbereich Physik and Landesforschungszentrum OPTIMAS, Rheinland-Pfälzische Technische Universität Kaiserslautern-Landau, 67663 Kaiserslautern, Germany

Microwave (MW) cavities offer a wide range of applications for exciting ferromagnetic resonance (FMR) in solid-state magnets [1]. Due to the interaction of resonant MW photons with the magnonic excitations of a magnetic sample, their coupling behaviour can be studied in detail [2]. In this study, we use a MW cavity designed to operate in the frequency range from 500 MHz to 600 MHz to investigate the thermally excited MW photons and their coupling to magnons in the ferrimagnetic insulator Y₃Fe₅O₁₂ (YIG). To this end, a 2 *m thick YIG film is positioned inside the cavity. The resonant coupling between the MW photons and the YIG FMR is realised. An active feedback loop inspired by a similar setup for surface acoustic wave resonators [3] is implemented to specifically amplify the thermal photons in the MW cavity, that couple to the magnetic excitations in YIG. The resonator used in combination with the active amplification process makes it possible to determine characteristic parameters of the coupled systems without the use of an external MW source.
[1] H.Huebl et. al, Phys. Rev. Lett. 111, 127003 (2013)
[2] L.Liensberger et. al, Phys. Rev. B 104, L100415 (2021)
[3] Z.Xi et. al, Phys. Rev. App. 23, 024054 (2025)

Keywords: Active Feedback Loop; Magnon-Photon Coupling; Microwave Cavities