Spectrum and losses of surface magnetostatic waves in a 1D magnon crystal

The spectrum and propagation losses of a surface magnetostatic wave in a 1D ferrite magnon crystal are experimentally studied as a function of angle φ between the wavevectors of the surface magnetostatic wave and periodic crystal lattice. Variation in the positions of Bragg forbidden bands with angle φ is described. A wide transmission band is discovered near long-wave frequency boundary f ₀ of the surface magnetostatic wave in a narrow interval of angles around φ ≈ 57°. In the interval 70° < φ < 90° and at frequencies below f ₀, there exists a magnetostatic wave with a wavevector that is normal to the bias field.     

Indicatrices of magnetostatic surface waves

Indicatrices (isofrequency curves) of magnetostatic surface waves are studied with allowance for wave attenuation. A bias magnetic field is applied tangentially to a ferrite film. Arbitrary angles between the bias magnetic field and the wave vector are examined.     

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)     

Propagation of magnetostatic backward surface waves in ferrite-insulator-metal structures magnetized by linearly nonuniform magnetic fields

A theoretical study is made of the trajectories and of the changes in magnitude and direction of the wave vectors of magnetostatic backward surface waves with different frequencies propagating in ferrite-insulator-metal structures with different insulating layer thicknesses and magnetized by a linearly nonuniform static field. It is shown that both forward and backward magnetostatic surface waves (MSSWs) propagate in a waveguide channel, on one side of which MSSWs undergo mirror reflection and on the other side of which their propagation direction is rotated, independently of the thickness of the insulator in the structure. It is shown that when MSSWs propagate in a nonuniform field, the forward wave is converted into a backward wave and, under certain conditions, the backward wave is converted into a forward wave. Some features of the propagation characteristics of magnetostatic backward surface waves are determined. Zh. Tekh. Fiz. 69, 70–77 (February 1999)     

Confinement of Bloch surface waves in a graphene-based one-dimensional photonic crystal and sensing applications

Bloch surface waves(BSWs) are excited in one-dimensional photonic crystals(Ph Cs) terminated by a graphene monolayer under the Kretschmann configuration. The field distribution and reflectance spectra are numerically calculated by the transverse magnetic method under transfer-matrix polarization, while the sensitivity is analyzed and compared with those of the surface plasmon resonance sensing method. It is found that the intensity of magnetic field is considerably enhanced in the region of the terminated layer of the multilayer stacks, and that BSW resonance appears only in the interface of the graphene and solution. Influences of the graphene layers and the thickness of a unit cell in Ph Cs on the reflectance are studied as well. In particular, by analyzing the performance of BSW sensors with the graphene monolayer,the wavelength sensitivity of the proposed sensor is 1040 nm/RIU whereas the angular sensitivity is 25.1?/RIU. In addition,the maximum of figure of merit can reach as high as 3000 RIU-1. Thus, by integrating graphene in a simple Kretschmann structure, one can obtain an enhancement of the light–graphene interaction, which is prospective for creating label-free,low-cost and high-sensitivity optical biosensors.     

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)     

Wave front reversal of surface magnetostatic waves

The wave front reversal (WFR) of non-reciprocal waves has been investigated. The experiment was performed using surface magnetostatic waves (SMSW) excited by a pulsed microwave signal of the carrier frequency ∼4.7 GHz in an epitaxial yttrium–iron garnet (YIG) film. The WFR was realized by pulsed parametric pumping of a double frequency. It was shown that WFR with high efficiency can be achieved for SMSW having relatively small wavenumbers k∼10² rad/cm.     

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)     

Propagation of nonlinear pulses of magnetostatic waves in coupled magnonic crystals

A periodic structure in the form of two coupled magnonic crystals in which the coupling allows effective control of nonlinear effects during propagation of magnetostatic waves is examined. The main specific features of the nonlinear effects are revealed in comparison with the periodic structure in the form of one magnonic crystal. The ability of the nonlinear coupler to suppress high- or lower-power signals for the functional processing of microwave-frequency signals is demonstrated.     

New nonlinear magnetostatic surface waves in a ferromagnetic (YIG)

The general propagation characteristics of magnetostatic surface waves guided by a single interface of a semi-infinite nonlinear dielectric cover and a ferromagnetic substrate (YIG) have been derived. The nonlinear dielectric cover has intensity dependent refractive indices. The magnetostatic approximation is considered and retardation is ignored in describing the electromagnetic fields in the structure. The used magnetostatic approximation is leading to new waves and might be called nonlinear magnetostatic surface waves. The propagation of these waves is non-reciprocal in contrast to the linear magnetostaic surface waves, which had been only found in the negative direction of propagation.     

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.     

一维非线性声波传播特性

针对一维非线性声波的传播问题进行了有限元仿真和实验研究. 首先推导了一维非线性声波方程的有限元形式, 含有高阶矩阵的非线性项导致声波具有波形畸变、谐波滋生、基频信号能量向高次谐波传递等非线性特性. 编制有限元程序对一维非线性声波进行了计算并对仿真得到的畸变非线性声波信号进行处理, 分析其传播性质和物理意义. 为验证有限元计算结果, 开展了水中的非线性声波传播的实验研究, 得到了不同输入信号幅度激励下和不同传播距离的畸变非线性声波信号. 然后对基波和二次谐波的传播性质进行详细讨论, 分析了二次谐波幅度与传播距离和输入信号幅度的变化关系及其意义, 拟合出二次谐波幅度随传播距离变化的方程并阐述了拟合方程的物理意义. 结果表明, 数值仿真信号及其频谱均与实验结果有较好的一致性, 证实计算方法和结果的正确性, 并提出了具有一定物理意义的二次谐波随传播距离变化的简单数学关系. 最后还对固体中的非线性声波传播性质进行了初步探讨. 本研究工作可为流体介质中的非线性声传播问题提供理论和实验依据.     

Dispersion characteristics of surface magnetostatic waves with dissipation

It is shown that unlike undamped waves, the dispersion characteristics of spin surface waves with dissipation have a maximum wave number at which there is a downward reversal in the dispersion curve of a wave number. This forms the upper branch of a dispersion curve with inverse dispersion and high attenuation, leading to an unclear frequency dependence of the wave vector. The lower primary dispersion branch corresponds to waves with forward dispersion, and attenuation is proportional to the small parameter of dissipation. However, the coefficient of wave attenuation grows sharply near the maximum wave number. Some angular and frequency limits of surface wave propagation change as well.     

Features of surface and volume magnetostatic waves in a tangentially magnetized slab

A special direction of the wave vector was found for volume magnetostatic waves (MSWs) that coincides with the cutoff angle for surface MSWs; when crossing this direction, the field configuration for MSWs with small wavenumbers changes sharply. It is shown that this direction corresponds to the maximum asymmetry of magnetostatic potential distribution over the film depth and the largest wave penetration depth into the film bulk from the surface. This effect occurs also for volume MSWs propagating in a wave channel.     

Propagation of acoustic waves in a one-dimensional macroscopically inhomogeneous poroelastic material

Wave propagation in macroscopically inhomogeneous porous materials has received much attention in recent years. The wave equation, derived from the alternative formulation of Biot's theory of 1962, was reduced and solved recently in the case of rigid frame inhomogeneous porous materials. This paper focuses on the solution of the full wave equation in which the acoustic and the elastic properties of the poroelastic material vary in one-dimension. The reflection coefficient of a one-dimensional macroscopically inhomogeneous porous material on a rigid backing is obtained numerically using the state vector (or the so-called Stroh) formalism and Peano series. This coefficient can then be used to straightforwardly calculate the scattered field. To validate the method of resolution, results obtained by the present method are compared to those calculated by the classical transfer matrix method at both normal and oblique incidence and to experimental measurements at normal incidence for a known two-layers porous material, considered as a single inhomogeneous layer. Finally, discussion about the absorption coefficient for various inhomogeneity profiles gives further perspectives.     

Transformation of surface magnetostatic waves channeled by a step bias field

The propagation of magnetostatic waves in a waveguide ferromagnetic channel formed by exposing a ferromagnetic film to a step bias is simulated. Both weak and strong channel couplings are considered. The dispersion characteristics and the distributions of wave functions are calculated. It is shown that the amplitudes of “half-waves” fitting into the channel width alternately increase and decrease with increasing frequency and the half-waves pass into the channel with the largest bias.     

Propagation of magnetostatic waves in the form of rectangular pulses in YIG films

The effect of dispersion on the propagation of linear rectangular pulses of magnetostatic waves in YIG films is studied. With surface magnetostatic waves propagating in YIG films and composite ferrite-insulator-metal structures, it is demonstrated that, for the near-rectangular phase-unmodulated input pulse and the distance between input and output transducers equal roughly to half the dispersion length of the pulse, the FWHM of the output pulses is 50–60% of the initial value. This fact can be used for estimating the dispersion coefficient of magnetostatic waves.