Numerical simulation of quasisurface magnetostatic waves in a ferrite film with two magnetic channels

Quasisurface magnetostatic waves propagating in a ferrite film along two magnetized channels are simulated numerically. It is shown that the interaction between the channels is manifested differently, depending on the wavelength. In the long-wavelength region the interaction between the channels has a distributed character; in the short-wavelength region the interaction between the channels appears as if it takes place at their boundary. The magnetized region of the ferrite film between the channels behaves both as a conductor of the alternating field and as a medium with eigenmodes, so that under certain conditions the waveguide can be transformed into a three-channel structure. The dispersion curves of the magnetostatic wave modes of a two-channel waveguide lie in zones bounded by the dispersion curves of the corresponding modes of a one-channel waveguide of double width. As the gap between the channels increases, the dispersion curves of the odd modes shift toward shorter wavelengths, and those of the even modes shift toward longer wavelengths. Zh. Tekh. Fiz. 68, 91–96 (February 1998)     

Theory of magnetostatic waves in a ferrite film with transition layers

A dispersion relation is derived for magnetostatic waves in a ferrite film with inhomogeneous layers near the interfaces. It is shown that the transition layers can be taken into account using a single integrated parameter, namely, the effective film thickness. It is established that the layered structure of the film causes an extra wave damping. The relations obtained can be used to analyze the dispersion and damping of the main modes of magnetostatic waves.     

Parametric interaction of magnetostatic waves with a nonstationary local pump

A solution is obtained for the general problem of the nonstationary interaction of backward volume magnetostatic waves in films of yttrium-iron garnet with local parametric pumping. In the case of a large pump region, l≫λ, where λ is the wavelength of the backward volume magnetostatic waves, the problem reduces to a system of truncated equations for two packets of counter propagating waves. In the opposite case, l<λ, the exact problem of parametric interactions of the eigenmodes of a ferrite film (both counterpropagating and in the same direction) is solved numerically. Both cases are studied experimentally and good qualitative and quantitative agreement is obtained with the theory. For the first time, the reversal of a wave front and the time reversal of the shape of backward volume magnetostatic wave pulses are observed and a change in the propagation time for the peak of the signal pulse and a reduction in its width owing to pumping are recorded. Two operating regimes are identified for a nonstationary parametric backward volume magnetostatic wave amplifier with local pumping, which differ in the ratio of the duration of the pump pulse to the transit time for the wave through the local pump region, and the effect of the parametric excitation of two-dimensional spin waves on the interaction of backward volume magnetostatic waves with a local nonstationary parametric pump is determined. Zh. éksp. Teor. Fiz. 116, 2192–2211 (December 1999)     

Nonlinear surface magnetostatic waves in a ferrite semiconductor structure

A theoretical analysis is made of the propagation of a nonlinear surface magnetostatic wave in a planar ferrite semiconductor structure as a function of the carrier concentration in the semiconductor layer. It is shown that for certain concentrations the surface magnetostatic wave is unstable with respect to longitudinal perturbations and may propagate perpendicular to the magnetic field in the form of solitons. Zh. Tekh. Fiz. 69, 119–121 (June 1999)     

Dependence of the frequencies of magnetostatic waves on the magnetizing field in ferrite films

Analytical expressions are derived for the derivatives of the frequencies of magnetostatic waves with respect to the external magnetic field in anisotropic ferromagnetic films. Films having cubic anisotropy and 〈100〉, 〈110〉, and 〈111〉 surfaces are analyzed in detail. The frequency-field relations are used in an experimental determination of the temperature coefficients of the cubic anisotropy field and the saturation magnetization in an yttrium iron garnet film. Fiz. Tverd. Tela (St. Petersburg) 40, 2089–2092 (November 1998)     

Influence of a constant magnetic field on the dispersion of surface magnetostatic waves in a structure consisting of ferrite and granular high-temperature superconductor

The dispersional properties of a surface magnetostatic wave (MSW) in a laminar structure consisting of ferrite film and a high-temperature superconducting (HTSC) layer are studied in detail. The propagation of surface MSW in this structure is investigated, and the dispersional equation is obtained; the granular character of the HTSC films and the influence of constant magnetic field are taken into account here. The magnetic field is responsible for breakdown of the Josephson layer of granular HTSC films and the appearance of nonsuperconducting layers close to the film surface. It follows from the calculation results that, when the HTSC film passes to the superconducting state, the dispersional characteristics of the MSW undergo a discontinuity. The magnitude of the discontinuity depends on the film thickness, the critical current, and the granule size. The results obtained may be used in designing various microelectronic devices based on granular HTSC films. Tomsk State Academy of Control Systems and Radioelectronics. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 6, pp. 72–77, June, 1996.     

Parametric excitation of spin waves in a nonlinear magnetostatic resonator

A theory of spin wave parametric instability is developed that simultaneously allows for cubic anisotropy and first- and second-order uniaxial anisotropies. The contributions of various anisotropies to a dispersion relation and first-and second-order nonlinearity coefficients are considered. A technique for studying the parametric instability of oscillations in magnetostatic resonators that relies on measuring their Q factors is proposed. Measuring data are used to determine the relaxation frequencies of parametrically excited spin waves in yttrium iron garnet films at frequencies close to 1 GHz. It is shown that a nonlinearity in the bias dependence of the spin wave frequencies should be allowed for in studying the relaxation parameters of ferrites.     

Propagation of magnetostatic waves in unsaturated ferrite films with a strip domain structure

The propagation of surface and volume magnetostatic waves in unsaturated films of yttrium iron garnet is studied experimentally for the case when the wavelength greatly exceeds the domain width, while the domain width is comparable to the film thickness. The characteristics of these waves are examined for symmetric linear, asymmetric linear, and symmetric zigzag strip domain structures in the films. These characteristics cannot be explained by a theory based on averaging the magnetization over all the domains. Zh. éksp. Teor. Fiz. 111, 1016–1031 (March 1997)     

Attenuation of surface magnetostatic waves in coupled ferrite plates

Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, Vol. 32, No. 11, pp. 1422–1429, November, 1989.     

Parametric interaction of volume and surface waves in a semiconfined relativistic plasma

Institute for Nuclear Research, Academy of Sciences of the Ukrainian SSR. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 32, No. 11, pp. 1358–1367, November, 1989.     

Parametric excitation of magnetostatic fluctuations by ion-cyclotron waves

It is shown that in an inhomogeneous plasma the magnetostatic fluctuations can be excited to superthermal level by ion-cyclotron waves. The growth rate of the ensuing parametric instability is calculated using some typical tokamak parameters.     

Cross-phase modulation of surface magnetostatic spin waves

This paper explains the modulation instability of two surface magnetostatic spin waves simultaneously propagating in a ferromagnetic film. Self-modulation of the spin waves appears when their power reaches a threshold, and this is a sign of cross-phase modulation. The parameters of the unstable process are calculated, and the gains of the perturbation amplitudes are determined. The results published earlier on the experimental detection of the cross-phase modulation of spin waves are explained. Zh. éksp. Teor. Fiz. 116, 2058–2068 (December 1999)     

Influence of cubic anisotropy on the temperature characteristics of magnetostatic waves in ferrite films magnetized in the film plane

Expressions for the temperature coefficients of frequency for magnetostatic waves in tangentially magnetized ferrite films having cubic anisotropy are obtained and analyzed. It is shown that in cases where the cubic axis lies in the plane of the film, temperature-induced changes in both the magnitude and direction of the external field can be used for thermostabilization of the frequencies. The problem of two-frequency thermostabilization is considered. The results of experimental investigations of the temperature characteristics of magnetization waves in a tangentially magnetized film of yttrium iron garnet with a {100} surface are presented. Zh. Tekh. Fiz. 68, 99–103 (October 1998)     

Coupled magnetostatic waves and beats of the envelope in a two-layer garnet ferrite structure

Interaction between forward bulk magnetostatic waves propagating in a structure consisting of two planar films separated by a nonmagnetic spacer is studied. When two modes are excited in the structure, a phase mismatch between them produces symmetric, asymmetric, and “forked” beats of the amplitudes of the magnetically coupled modes. It is shown that the parameters of the beats can be controlled by varying the magnetic field intensity and ration between the initial amplitudes of the modes excited in the structure.     

Spatiotemporal dynamics of magnetostatic and spin waves in a transversely confined ferrite waveguide

Spatiotemporal dynamics of the multimodal propagation of magnetostatic waves in a transversally confined ferrite waveguide and the parametric excitation of spin wave under conditions of three-magnon decay processes are experimentally investigated by the Brillouin spectroscopy.