Control of Magnon-Photon Coupling Strength in a Planar Resonator/Yttrium-Iron-Garnet Thin-Film Configuration

A systematic study of the coupling at room temperature between ferromagnetic resonance and a planar resonator is presented. The chosen magnetic material is a ferrimagnetic insulator (yttrium iron garnet, YIG) which is positioned on top of a stop band (notch) filter based on a stub line capacitively coupled to a 50 Ω microstrip line resonating at 4.731 GHz. Control of the magnon-photon coupling strength is discussed in terms of the microwave excitation configuration and the YIG thickness from 0.2 to 41 μm. From the latter dependence, we extract a single spin-photon coupling of g
₀
/2π = 162 ± 6 mHz and a maximum of an effective coupling of 290 MHz.