Peculiarities of the formation of band gaps in multimode regime of spin waves propagation in magnonic crystals

The dynamics of spin waves during their multimode propagation in a magnonic crystal, which is an irregular narrow ferrite waveguide with periodic boundary modulation, has been studied by the method of Mandelstam–Brillouin spectroscopy. The transformation of the mode composition of spin waves propagating in an irregular ferrite waveguide is shown. The space-time dynamics of spin waves and the characteristics of the band gaps of a magnonic crystal are experimentally studied, and the possibility of controlling the frequency-selective properties of such a structure is shown. By excitation of a superposition of even or odd width modes of the ferrite microstructure, it becomes possible to control the position of the band gaps of a magnonic crystal. The results of the experiment agree with the results of micromagnetic modeling of the propagation and transformation of the spectrum of spin waves propagating in a ferromagnetic periodic structure.