Studying the spectra of thermal magnons in composite materials with embedded magnetite nanoparticles using Brillouin light-scattering spectroscopy

We describe the preparation of multilayer composite coating comprising nanoparticles of magnetite on metal substrates previously modified by sonication. Using the Brillouin light-scattering method, we have investigated the spectral characteristics of thermal magnons in these films as a function of the number of layers and the external magnetic-field strength.     

Generation of chaotic microwave pulses with the help of passive synchronization of spin wave self-modulation frequencies in self-oscillatory ring systems

Passive synchronization (PS) of spin wave self-modulation frequencies of a chaotic microwave signal has been observed for the first time in a self-oscillatory ring system involving a nonlinear passive element with saturable absorption. The development of PS led to the generation of a periodic train of chaotic microwave pulses with an off/duty ratio exceeding 20. It is established that the repetition period of chaotic microwave pulses can be controlled by changing gain in the ring system.     

Magnetostatic surface waves in a ferrite–ferromagnetic metal layered medium based on yttrium iron garnet epitaxial films and TbCo<Subscript>2</Subscript>/FeCo nanostructures

The effect of a thin ferromagnetic metal layer placed on the surface of an yttrium iron garnet surface on the spectrum and loss of magnetostatic surface waves (MSSWs) is experimentally investigated in the case of homogeneous metallization and in the case of a system of periodic metal strips. It is shown that essential attenuation is produced by a metal layer whose thickness is substantially smaller than the depth of the skin layer appearing when an MSSW propagates along a ferromagnetic–metal boundary. The presence of the MSSW reflection by the boundary between the metallic and nonmetallic parts of a ferromagnetic film is experimentally confirmed by the Mandelstam–Brillouin spectroscopy.     

Effect of ferrite magnonic crystal metallization on Bragg resonances of magnetostatic surface waves

It is experimentally established that metallization of the surface of a ferrite magnonic crystal destroys the Bragg resonances of magnetostatic surface waves by violating the conditions of phase synchronism of the incident wave and that reflected from the periodic surface structure.     

Passage of two-frequency signals in the Bragg resonance band of a one-dimensional magnon crystal

Passage of a two-frequency signal with high and low power levels through a spin-wave transmission line with a one-dimensional periodic microstructure formed on the surface of a ferromagnetic film is experimentally studied. Experiments are carried out under the condition of three-wave parametric instability of spin waves. It is shown that, near the central frequency of the first Bragg resonance at certain power levels of the large and small signals, the nonlinear spin-wave transmission line can operate as either a power limiter or a signal-to-noise enhancer.     

The electrodynamic characteristics of a finite-width metal/dielectric/ferroelectric/dielectric/metal layer structure

The electrodynamic characteristics of a finite-width metal/dielectric/ferroelectric/dielectric/metal layer structure are investigated. The eigenmode spectra, field distributions, and dispersion characteristics are calculated with the help of simulation based on the finite element method. It is demonstrated that the properties of the width modes of the layer structure can be controlled through changing the external electric and magnetic fields.     

The influence of a metal on transverse characteristics of hybrid waves in a layered ferrite–ferroelectric structure

We present electrodynamic characteristics of a layered multiferroic structure of metal–dielectric–ferrite–dielectric–ferroelectric–dielectric–metal type calculated by the finite elements method. Properties of transverse modes of hybrid waves (dispersion characteristics, electric field distribution at different frequencies, and damping rate) as functions of the distance between the ferroelectric layer and the metal screen are analyzed for the first time.     

Wideband chaotic microwave signal generation in a ring system with a nonlinear delay line on coupled ferromagnetic films

Various regimes of chaotic signal generation have been studied in an self-oscillating ring system with a wideband nonlinear delay line based on coupled ferromagnetic films, in which magnetostatic backward volume waves (MSBVWs) are excited. It is shown for the first time that the simultaneous excitation of two waves in the coupled films leads to the appearance of a falling part in the dynamic characteristic of the MSBVW delay line and the generation of a broadband chaotic signal with a continuous spectrum. Under certain conditions, the ring exhibits a regime of intermittency, in which broadband chaotic signals with both continuous and discrete spectra are generated.     

Influence of the amplitude and phase nonlinearity of a spin-wave delay line on the wideband chaotic microwave generation

Regimes of wideband chaotic microwave generation have been studied in a self-oscillating ring system with a nonlinear delay line, in which magnetostatic backward volume waves (MSBVWs) are excited. It is established that a change in length of the delay line influences on its amplitude and phase nonlineartity, thus making it possible to control the characteristics of the chaotic microwave signal generated in the ring. It is demonstrated for the first time that a wideband chaotic microwave signal with a continuous spectrum and a nearly Gaussian probability density distribution can be generated by exciting MSBVWs in a self-oscillating ring system with a nonlinear delay line based on single ferromagnetic film.     

Generation of chaotic dissipative solitons in active ring resonator with one-dimensional periodic ferromagnetic miscrostructure

Generation of chaotic dissipative solitons has been observed in an active ring resonator with one-dimensional periodic ferromagnetic microstructure comprising a single-crystalline film of yttrium iron garnet (YIG) with a lattice of grooves oriented perpendicular to the direction of propagation of a magnetostatic surface wave (MSSW). A quasi-periodic train of chaotic dissipative solitons was generated in this system under the conditions of three-magnon processes of MSSW decay due to the passive synchronization (PS) of spin wave self-modulation in a frequency band corresponding to the first bandgap. The PS onset was caused by the saturable absorption of microwave signals within the bandgap of the MSSW transmission line.