Resonance properties of bi-component arrays of magnetic dots magnetized perpendicular to their planes

The spin wave spectrum of dense arrays of rectangular elements periodically arranged in a two-dimensional magnonic crystal with a complex unit cell and magnetized perpendicularly to the array plane has been characterized using broadband ferromagnetic resonance (FMR) spectroscopy. The crystal's unit cell consists of non-collinear orientations of constituting elongated rectangular elements. We found that only one mode is excited in the perpendicular-to-plane FMR in complete magnetic saturation. We also conducted out-of-plane angle resolved measurements of the FMR resonance field. We observe splitting of the singlet observed for the perfect perpendicular-to-plane orientation of the applied field into a doublet upon a tilt of the field from this orientation. The splitting of the singlet into a doublet is explained as an experimental evidence of dipole coupling of the elements on the arrays. Our experimental observations are in good agreement with the theory we developed to describe the magnetization dynamics on this periodic array.