Influence of the Coupling Mechanism on Spin Wave Spectra in a Microwave Waveguide–Ring Resonator System Based on YIG Films

Abstract

This work investigates the propagation of spin waves in an integrated structure based on a yttrium iron garnet (YIG) film containing a square ring resonator and a microwave waveguide. Using micromagnetic modeling, we perform a comparative analysis of two coupling topologies: with direct magnetic contact and with a $10 \mu \mathrm{m}$ gap. We demonstrate that varying the external magnetic field angle in the quasi-longitudinal range (–15° to +15°) induces spatial inhomogeneity of the effective magnetic field due to the geometric anisotropy of the square contour, leading to a controlled shift of resonance frequencies while maintaining high quality factor. The angular tuning mechanism is common to both configurations; however, the presence of a gap modifies the transmitted signal amplitude and introduces additional phase delay through the evanescent coupling mechanism. Analysis of dynamic magnetization maps reveals a transition from symmetric azimuthal modes to mixed modes upon field angle deviation. The results demonstrate dual control of frequency selectivity and prospects for tunable magnonic filters.