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.

The paper presents the theoretical study results of the dispersion characteristics of electromagnet-ic waves existing in antiferromagnetic (AFM) metamaterial. The AFM metamaterial consists of a transversely magnetized antiferromagnet, inside of which a two-dimensional periodic structure of thin conducting wires surrounded by insulators is placed. It has been established that the AFM metamaterial has two frequency ranges, in which there are backward waves, and the material pa-rameters of the medium are twice negative. The indicated areas are located in the terahertz range.

The paper presents the theoretical study results of the control of the spectrum of slow electromagnetic waves (EMWs) existing in a “left-handed” medium based on a magnetically active plasma metamaterial. The investigated metamaterial is a strip waveguide completely filled with a longitudinally magnetized “cold” electron plasma, containing a periodic structure of perfectly conducting split-ring resonators (SRRs). It is shown that either one (ordinary), either two (ordinary and unordinary) slow EMWs can exist in a “left-handed” medium based on the magnetically active plasma and the spectrum of these waves depends on the SRR own frequency and magnetic induction. The unordinary slow EMW possesses by the negative dispersion and the dispersion characteristic of the ordinary EMW has the sections with both the negative and positive dispersions.

The results of a theoretical study of the electrodynamic characteristics of fast and slow electromagnetic waves (EMWs) propagating in a metamaterial are presented. The metamaterial consists of a ferromagnetic film inside which a periodic lattice of thin metal wires is located. It has been established that the ferromagnetic thin-film metamaterial possesses the properties of a left-handed medium at frequencies of slow electromagnetic waves. It is shown that, in a ferromagnetic metamaterial, compared with a conventional ferromagnetic film, the cutoff frequencies of fast and slow EMWs shift to a higher frequency range, and EMWs themselves become strongly slowed waves.

AbstractWe present experimental data on the development of chaotic oscillations in a nonautonomous magnetoacoustic oscillator based on a hybrid magnetoacoustic resonator of the reflection type. The proposed oscillator exhibits regimes of quasi-periodic and chaotic generation under an external low-frequency periodic force. The chaotic dynamics of the magnetoacoustic oscillator is caused by the presence of delay and bistability in the system.