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The periodic structure in the form of two coupled magnonic crystals (MCs) was considered for the first time. It was shown that the variation of coupling allows to control effectively the characteristics of the bandgaps in the spectrum of magnetostatic spin waves. Main features of formation of the bandgaps were investigated in the basis of theoretical and experimental results. The comparison with a periodic structure in the form of a single MC was provided. The possibility of formation of two frequency bandgaps and shift of the frequency bandgaps depending on coupling was demonstrated in the frequency region of the first Bragg resonance. It was shown that the control of bandgaps in such structure gives additional opportunities to create microwave filters and phase shifters with desired characteristics. [ABSTRACT FROM AUTHOR]

It is predicted that in 2D magnonic crystals the edge rotational magnons of forward volume magnetostatic spin waves can exist. Under certain conditions, locally bounded magnons may appear within the crystal consisting of the ferromagnetic matrix and periodically inserted magnetic/non-magnetic inclusions. It is also shown that interplay of different resonances in 2D magnonic crystal may provide conditions for spin wave modes existence with negative group velocity. [ABSTRACT FROM AUTHOR]

This study reports on the experimental results of chaotic microwave (MW) pulse generation in a ferromagnetic film ring oscillator under pulse-modulated (PM) and narrowband noise forces. Chaotic dynamics of the investigated self-oscillatory system is produced through three-wave parametric interactions of spin waves. It is shown, that periodical sequences of chaotic MW pulses are generated under a PM force and solitary chaotic MW pulses are generated under a noise force. Such pulses are formed through forced chaos synchronization. For description of forced chaos synchronization phenomenon, a ferromagnetic film ring oscillator model with nonlinear amplification and delay time is constructed. This model is based on the use of the Landau–Lifshitz equation, magnetostatic approximation and the Holstein–Primakoff transformation. Calculation results of chaos suppression under an external harmonic force are demonstrated. [ABSTRACT FROM AUTHOR]

This study reports on a dissipative soliton oscillator utilizing two nonlinear magnetostatic spin wave (MSW) devices in a feedback loop. Both nonlinear MSW devices [a spin wave transmission line (TL) and a signal-to-noise enhancer (SNE)] operate in the frequency band where three-wave parametric processes are allowed. Self-generation of a complex-modulated MW signal is caused by nonlinearity of the spin wave TL. The SNE carries out a passive locking of the spin wave self-modulation frequencies and forms the dissipative soliton trains. It is shown, that electronic control of a repetition interval and pulse ratio of dissipative solitons is realized by the change of a klystron beam current. [ABSTRACT FROM PUBLISHER]

Self-generation of chaotic dissipative soliton trains was observed in an active ring resonator based on 1-D periodical ferromagnetic structure (1-D magnonic crystal) in a groove's grating form. The grooves were cut off on the surface of yttrium iron garnet film with the help of a scribing technique and placed perpendicularly to the magnetostatic surface wave (MSSW) propagation. The presence of three magnon decay processes of MSSW, a frequency filtration, and a passive synchronization of the spin-wave self-modulation frequencies caused the self-generation of chaotic dissipative soliton trains. Passive synchronization was realized at frequencies of the first band gap because of the presence of a saturable absorption of a microwave signal. [ABSTRACT FROM AUTHOR]

We investigate theoretically and experimentally magnonic bandgaps in a 1-D magnonic crystal consisting of a yttrium iron garnet film with periodically modulated thickness in contact with a metal. The theoretical model is based on the frequency-domain finite element method. The presented measurements of the transmitted spin-wave signal were performed with a vector network analyzer with coplanar and microstripe waveguide antennas for a magnonic crystal with and without metallic overlayer, respectively. The obtained results confirm that the presence of a metallic layer on top of the magnonic crystal shifts up the frequency of magnonic bandgaps. [ABSTRACT FROM AUTHOR]

A general theory of forward volume magnetostatic spin-wave multiple scattering by a finite two-dimensional ensemble of cylindrical magnetic inclusions in a ferromagnetic film (matrix) metallized from both sides is developed. It is predicted that bound spin-wave modes are excited around these inclusions. The set of self-consistent equations for spin-wave multiple scattering inside the matrix with inclusions is obtained by using an invariant addition theorem for the cylindrical wave functions. This set of equations is solved by an iterative process. We derive simple expressions for eigenmodes (bound modes) in a form of Bloch-like spin waves propagating along the inclusion circular array. The theory is illustrated on practically significant examples: (i) bound-mode excitation by propagating spin waves; (ii) helix components of the spin-wave-scattered field around magnetic inclusions; and (iii) a high-quality spin-wave resonator based on a small number of magnetic inclusions. [ABSTRACT FROM AUTHOR]