Magnetostatic Surface-Wave Propagation in Ferrite Thin Films with Arbitrary Variations of the Magnetization Through the Film Thickness

A variational formulation for the magnetostatic problem in an anisotropic and inhomogeneous region bounded by perfect conductors is described. The method is applied to the special case of magnetostatic surface-wave (MSSW) modes propagating in a ferrite thin film with arbitrary variations of the saturation magnetization through the film thickness. Methods for calculating dispersion relations, delay characteristics, and magnetostatic potential functions are discussed. The functional that is minimized is interpreted in terms of contributions to the mode energy. Also, concepts pertaining to homogeneous films such as mode bandwidth and dimensional scaling effects are extended to the general inhomogeneous case. Calculations for a two-layer film with a gradual transition region and an ion-implanted film are presented as numerical examples.     

Anisotropy Characteristics of Magnetostatic Surface Wave Propagating in YIG/Dielectric/Metal Layered Structure

The anisotropy of magnetostatic surface wave (MSSW) propagating in finite width YIG/dielectric/metal layered structure is analyzed. This problem is solved by finding the rigorous solution of each layer from Maxwell equation and the appropriate transmission Green's function matrix (G). From the relationship of Green's function matrixes of dielectric layer and ferrite layer, the dispersion equation is obtained.The MSSW filter is designed to verify the dispersion characteristics. The experiment results are in good agreement with the calculating data from the model.     

Application of the smith chart in the analysis of the relaxation properties of magnetostatic oscillations and spin waves in ferrite films

The relaxation properties of three main types of magnetostatic oscillations in a magnetostatic film resonator and nonlinear processes (parametric excitation of spin waves in the first and second bands in the presence of the tangential magnetization of the gallium-substituted yttrium-iron garnet film and foldover in the regime of normal magnetization) are studied in the frequency range 0.8–4.5 GHz. An original method is proposed for the determination of thresholds of the parametric excitation of spin waves using the deformations of Smith chart caused by variations in the measurement power level. The method is used in the highaccuracy analysis of the frequency dependences of threshold power in the presence of tangential magnetization in the regimes of resonances of both surface and backward volume magnetostatic waves. The frequencyfield dependences of the absorption spectra of three main types of magnetostatic oscillations in the linear regime are used to determine the saturation magnetization, anisotropy fields, and unloaded Q factors of resonator at each mode and to calculate the relaxation parameters of the corresponding magnetostatic oscillations. The experimentally measured threshold pump powers are used to calculate the relaxation line widths of the parametrically excited spin waves with the aid of the improved theory of parametric processes that takes into account both cubic and uniaxial anisotropy of the film.     

Propagation characteristics of magnetostatic waves

The present paper reviews the propagation characteristics of the three magnetostatic wave-types that can exist in a ferrimagnetic film such as the commonly used epitaxial yttrium-iron-garnet (YIG) film, viz., magnetostatic surface waves (MSSWs), magnetostatic forward volume waves (MSFVWs) and magnetostatic backward volume waves (MSBVWs). The pronounced inherent dispersiveness of these waves and methods of controlling or tailoring dispersion are discussed. Other propagation characteristics such as diffraction and propagation loss and the envelope distortion of acw pulse in propagating through such a dispersive medium are briefly described.     

Scattering of forward bulk magnetostatic waves by a defect of the surface of a ferromagnetic film magnetized at an arbitrary angle

The solution for the diffraction problem of scattering of magnetostatic waves by an arbitrary shallow defect situated under the surface of a ferromagnetic film magnetized at an arbitrary angle is obtained in the quasi-static approximation. Expressions for the energy flux density of scattered magnetostatic waves in the far-field zone are found. The results of computations of the time-averaged flux density of bulk magnetostatic waves reflected from rectangular and circular shallow irregularities are presented.     

Dispersion characteristics of magnetostatic surface waves in a two-layer ferromagnetic film

The dispersion characteristics (dispersion and isofrequency curves and dispersion surfaces) of magnetostatic surface waves propagating in an arbitrary direction in a two-layer ferromagnetic film are investigated. The shapes of these curves and surfaces are studied at different ratios between the saturation magnetizations of the ferromagnetic layers, and the conditions for existence of external waves (always forward) and internal waves (forward and backward or only forward) are determined.     

Surface waves on a grounded anisotropic plasma slab

The dispersion relations of the plane surface waves supported by a grounded magnetoplasma slab immersed in free space are discussed for the case in which the magnetostatic field is parallel to both the direction of propagation and the vacuum-plasma interface. The dependence of the surface-wave characteristics on the thickness of the plasma slab and the strength of the magnetostatic field is also examined.     

Analysis of the distribution of magnetostatic surface waves by scanning the surface of a ferrite slab

A technique for the experimental visualization of the distribution of the amplitudes and phases of the magnetostatic waves propagating in ferrite-film structures is developed. It is shown that applying the Fourier transform to the data obtained with the use of this technique, it is possible to investigate the mode composition of the magnetostatic waves and find dispersion dependences for each mode. On the basis of the proposed technique, distributions of magnetostatic surface waves in bilateral samples of ferrite films are investigated. It is found that, at a wavelength comparable with the substrate thickness, the ferrite film at the opposite side of the substrate significantly changes the wave distribution in the sample and causes spatial beating along the propagation axis.     

Plasma resonance guiding of surface magnetoplasmons by thin semiconductor films

Theoretical investigation on surface magnetoplasmons maintained by the plasma resonance in a thin (comparing to the wavelength) semiconducting film placed on a perfectly conducting substrate is presented. Dispersion characteristics and nonreciprocal behaviour of surface magnetoplasmons are studied for arbitrary orientation of externally applied magnetostatic field and for various profiles of film inhomogeneity.     

Diffraction of surface magnetostatic waves by surface cavities on ferromagnetic film

The diffraction problem of the scattering of surface magnetostatic waves by shallow rectangular and circular cavities on the surface of a ferromagnetic film that is tangentially magnetized with respect to the surface is numerically analyzed in the magnetostatic approximation.     

Evaluation of loss factor of multilayered inhomogeneous waveguidesfor magnetostatic waves using efficient finite element formalism

An efficient finite-element solution procedure is developed for calculating propagation losses of magnetostatic waves in multilayered inhomogeneous waveguides. The final matrix equation is reduced to a standard complex eigenvalue problem whose eigenvalue corresponds to the complex phase constant itself. Thus, iteration procedures are not necessary and the phase and attenuation constants can be directly obtained by solving a standard eigenvalue equation. The validity of the method is confirmed by calculating propagation losses of magnetostatic surface waves in a single yttrium-iron-garnet (YIG)-film structure. Numerical results for a triple-layered YIG film structure are also presented. It is found that, in the triple-layered structure, propagation losses are highly dependent on the linewidth of the film in which the magnetostatic potential is well confined     

Ray Optic Approach to Magnetostatic Bulk Wave Propagation in a YIG Film Delay Line

This paper discusses a ray optic approach to the magnetostatic wave propagation in a normally magnetized YIG film. The dispersion relation is obtained using the method of transverse resonance. The Iateral shift due to reflection at the boundaries has been obtained from energy flow analysis. The path of the rays has been traced from which an approximate expression for the group delay time has been obtained. It is seen that, for the first-order mode, the agreement between this approximate expression for the delay with the rigorous one is satisfactory except near the lower cutoff. In the case of higher order, modes the two compare satisfactorily throughout the frequency range of guided waves.     

Edge-Guided Magnetostatic Mode in a Ridged-Type Waveguide (Short Papers)

A ridged-type magnetostatic waveguide is analyzed using the boundary element method. A bias magnetic field is applied perpendicularly to the surface of an yttrium-iron-garnet (YIG) film grown on a gadlinium-gallium-garnet (GGG) substrate. The dispersion curves and the potential profiles obtained in this paper show that the mode has a strong nonreciprocal property and is a kind of edge-guided mode which propagates along either side of the ridge, depending upon the direction of the bias field and the direction of the wave propagation. In addition, the authors emphasize the fact that the boundary element method is useful for analysis of a complex structure in the field of magnetostatic wave (MSW) devices.     

The magnetostatic waves in ferrite film with losses

The influence of relaxation processes on dispersion equation solutions for surface and volume magnetostatic waves (MSW) propagating in a ferrite film is theoretically investigated. It is shown that dissipation is the main reason for the appearance of complementary MSW branches in frequency intervals which adjoin standard branches in spectra. The existence of threshold MSW wave numbers which upper bound the spectra of possible wave numbers is established. Asymptotic frequencies anf frequencies corresponding to the threshold values of wave numbers are calculated. The effects of dissipation on the ranges in which MSW exist are calculated. The frequency dispersion of the loss spectra is also calculated     

Directional coupling of magnetostatic surface waves in layered magnetic thin films

The propagation characteristics of magnetostatic surface waves (m.s.s.w.) in a layered system of y.i.g. film, dielectric, y.i.g. film, are theoretically investigated. It is shown that the directional coupling of m.s.s.w. is possible between y.i.g. films. The directional coupling has frequency filtering characteristics due to dispersion of m.s.s.w.     

Magnetostatic waves in a tangentially magnetized ferrite plate with a normal uniaxial anisotropy under the conditions for orientational transition

Propagation of magnetostatic waves in a tangentially magnetized ferrite plate with a normal uniaxial anisotropy under the conditions for the orientational phase transition of the second order is considered. Dispersion relations for quasi-surface and quasi-volume magnetostatic waves with the wave vector arbitrarily oriented in the plane of the plate have been obtained. The limiting frequencies of the regions of existence of both modes have been determined and the dependences of these frequencies on the anisotropy field and wave-vector orientation have been investigated.     

Magnetostatic surface waves in a ferrite/dielectric/metal-strip-grating structure

The dispersion relation for magnetostatic surface waves in a ferrite/dielectric/metal-strip-grating structure is obtained. It is shown that dispersion of magnetostatic surface waves must be qualitatively the same as in a ferrite/dielectric/metal structure, while the slope of the dispersion curve in the region of backward magnetostatic waves existing in a ferrite/dielectric/grating structure (and in a ferrite/grating structure in particular) is considerably higher than the slope of this curve corresponding to a ferrite/dielectric/metal structure. It is found that this phenomenon can be explained by the dependence of the grating’s shielding capability on the wave number of magnetostatic surface waves. A grating shielding parameter is introduced and dependences of this parameter on the wave number that can be used to explain the phenomena observed in the experiment are determined.     

微波静磁波模式特性分析

全面分析了磁光薄膜波导中磁化方向对微波静磁波传播模式的影响。给出了不同模式的静磁波色散方程和带宽的一般表达式,首次完整地展现了静磁波的模式分布图。所得结论可用于分析倾斜磁场在改善基于静磁波的新型磁光B ragg器件衍射性能方面所起的作用。     

双层YIG波导中静磁体波的传播特性

本文研究了在倾斜静磁场作用下,双层YIG薄膜波导结构中静磁体波的传播特性,得到了其色散的特征方程,计算了磁场倾角从5°到20°范围内双层波导结构中静磁体波传播的色散关系和延迟特性.结果表明,斜向场情况下在双层YIG薄膜结构中传播的静磁体波适合应用于高频范围,并且通过调节磁场倾角可以获得比单层膜波导结构更好的延迟率可调范围.斜向场情况下采用双层YIG薄膜结构,对于改进静磁波器件和磁光波导器件的性能具有十分重要的意义.     

Finite-element analysis of magnetostatic wave propagation in a YIGfilm of finite dimensions

A unified numerical approach based on the finite-element method is described for the magnetostatic wave propagation in a YIG film of finite dimensions. Both magnetostatic surface wave modes are treated. The validity of the method is confirmed by calculating the magnetostatic wave modes in a YIG-loaded rectangular waveguide and in a YIG film of finite width. The numerical results of a YIG films with nonuniform bias field along the film width are also presented, and the effects of bias field distributions on the delay characteristics and potential profiles are examined