Direct probing of strong magnon–photon coupling in a planar geometry

We demonstrate direct probing of strong magnon–photon coupling using Brillouin light scattering (BLS) spectroscopy in a planar geometry. The magnonic hybrid system comprises a split-ring resonator loaded with epitaxial yttrium iron garnet thin films of 200 nm and 2.46 μm thickness. The BLS measurements are combined with microwave spectroscopy measurements where both biasing magnetic field and microwave excitation frequency are varied. The cooperativity for the 200 nm-thick YIG films is 1.1, and larger cooperativity of 29.1 is found for the 2.46 μm-thick YIG film. We show that BLS is advantageous for probing the magnonic character of magnon–photon polaritons, while microwave absorption is more sensitive to the photonic character of the hybrid excitation. A miniaturized, planar device design is imperative for the potential integration of magnonic hybrid systems in future coherent information technologies, and our results are a first stepping stone in this regard. Furthermore, successfully detecting the magnonic hybrid excitation by BLS is an essential step for the up-conversion of quantum signals from the microwave to the optical regime in hybrid quantum systems.
This is the Accepted Manuscript version of an article accepted for publication in Quantum Science and Technology. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The Version of Record is available online at This article will be embargoed until 10/31/2023.
magnon, Brillouin light scattering, microwave spectroscopy, ferromagnetic resonance, light matter interaction, spin waves, magnon photon coupling
Kaffash, Mojtaba T., Dinesh Wagle, Anish Rai, Thomas Meyer, John Q. Xiao, and M. Benjamin Jungfleisch. “Direct Probing of Strong Magnon–Photon Coupling in a Planar Geometry.” Quantum Science and Technology 8, no. 1 (October 2022): 01LT02.