Magnetostatic Surface Waves Research Articles

Full-wave analysis of the excitation of magnetostatic-surface waves by a semi-infinite microstrip transducer - theory and experiment

This paper presents a new method for the complete characterization of the radiation of magnetostatic-surface waves in microstrip transmission lines with longitudinal magnetization. This method is based on the analysis of the excitation of leaky modes in microstrip lines and provides both the propagation constant and the complex impedance of the microstrip. From these quantities, the radiation resistance and other relevant characteristics of the line can be directly obtained.

Surface magnetostatic waves and magnetic polaritons at the junction of the magnetic superlattice and magnetic material

Using electromagnetic wave theory in the Voigt configuration, the surface magnetostatic waves (MW) and magnetic polaritons localized at the junction between semi-infinite magnetic superlattice (SL) and magnetic material are analysed theoretically. The general dispersion relation for localized MW and magnetic polaritons are derived by the transfer matrix method in the long-wavelength limit. Some examples of the wave spectra are presented for SL composed of two magnetic materials (Fe/Co). The dispersion curves for different contact materials (contact material with Ni, Co and Gd, respectively) are calculated numerically and the ranges within which surface modes frequencies lie are discussed.

An analysis of excitation of magnetostatic surface waves in an in-plane magnetized YIG film by the integral kernel expansion method

We present a method to solve a kind of integral equations (we call it the integral kernel expansion method), and apply it to an analysis of excitation of magnetostatic surface-wave/magnetostatic backward-volume-wave modes in a magnetized yttrium-iron-garnet film. The Fourier integral of a normal component of magnetic flux density is derived in terms of an unknown current density flowing in a microstrip transducer. The integral kernel is expanded into a series of the Legendre polynomials and expansion of the unknown current density in terms of appropriate functions reduces the Fourier integral to a system of linear equations with unknown coefficients. Determination of the unknown coefficients allows us to estimate the power of magnetostatic waves, which characterizes the excitation. It is found that our numerical method is superior to the previous conventional method based on an assumed current density. In order to verify the validity of our method, we compare our results with the corresponding experiments, and we have found good agreement between the two.

Surface magnetostatic spin wave envelope solitons in ferrite semiconductor structure

A theoretical analysis of the nonlinear properties of exchange-free magnetostatic surface waves in a layered structure containing ferromagnet and semiconductor films is presented. Criteria for the existence of bright surface spin wave envelope solitons are given. Their existence is only guaranteed for rather particular regions of the spin wave spectrum. These are demonstrated numerically by using yttrium iron garnet-indium antimonide and yttrium iron garnet-gallium arsenide structures.

YIG 단결정 박막에 대한 정자파의 온도의존성 연구

LPE(liquid phase epitaxy)방법으로 제작한 YIG 단결정 박막의 정자파(MSW; magnetostatic wave) 모드의 온도의존성을 조사하기 위하여 온도를 -14<TEX>$0^{\circ}C$</TEX>에서 20<TEX>$0^{\circ}C$</TEX>까지 2<TEX>$0^{\circ}C$</TEX>간격으로 변화하면서 강자성공명 실험을 하였다. 시편면과 외부자기장을 평행하게 가할 때 모든 온도에서 주기적인 신호로 나타나는 정자표면파와 정자역체적파 모드를 관측하였다 온도가 감소함에 따라 정자파 모드들은 저자장쪽으로 이동하고 세기가 감소하였고, 각 모드들 사이의 간격은 증가하였다. 온도변화에 따른 정자파 모드를 Walker와 Damon-Eshbach 이론으로 분석한 결과 잘 일치하였다. 온도별로 계산한 포화자화값은 온도가 감소함에 따라 증가하였다. 관측된 정자파 모드의 선폭은 온돈가 감소함에 따라 다양하게 변화하였다. In order to study the temperature dependence of the magnetostatic wave modes for an YIG thin film, grown by a liquid phase epitaxy method, The ferromagnetic resonance was performed by an FMR spectrometer in the temperature range -140<TEX>$\^{C}$</TEX>∼200<TEX>$\^{C}$</TEX>. The magnetostatic surface wave and backward volume wave modes show periodic excitations in parallel configuration. The resonance fields of all modes and intensities decreased with decreasing the temperature. All magnetostatic modes can be well explained by the Walker and Damon-Eshbach theory. The calculated saturation magnetization Ms of the YIG thin film was increased with decreasing the temperature. The line widths of magnetostatic modes changed in various trends with decreasing the temperature.

Nonlinear magnetostatic surface waves pulse propagation in ferrite-dielectric-metal structure

The influence of the modulation and parametric four-magnon instabilities on the propagation of magnetostatic surface wave (MSSW) pulses in a delay line configuration has been experimentally studied in a ferrite-dielectric-metal structure. It was possible to distinguish the influence of both instabilities by changing the dispersion properties of the exploited device. The contribution of additional MSSW continuous wave and pulsed signals on the propagation of MSSW pulses has been also considered.

Nonlinear behavior of magnetostatic surface waves in ferrite-film multilayer structure

The nonlinear interaction of magnetostatic surface waves propagated along ferrite-film double-layer structure has been investigated theoretically. The possibility of the nonlinear directional coupler has been shown for the waveguide structure by solving numerically the coupled nonlinear Schrodinger equations. In addition, it is shown that bright soliton-like behavior can be seen in the structure.

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.

Nonlinear magneto-optic measurement of flux propagation dynamics in thin Permalloy films

Time-resolved nonlinear optics are used to study the propagation of magnetic flux pulses in a 250 nm Permalloy film. The flux is generated in the film by coupling it to a coplanar waveguide structure driven with broadband voltage pulses. Flux pulses propagated in the film with a phase velocity of 4.2×105 m/s and a group velocity of 1.5×105 m/s. Both velocities are consistent with the predictions of Damon–Eshbach theory for magnetostatic surface waves with 200–300 μm wavelengths. Within 100 μm of the excitation source, flux pulses decayed monotonically but with no measurable delay.

Excitation and Reception of Electromagnetic, Magnetostatic and Spin Waves in Ferrite Films

The paper presents a new universal formulation of electromagnetic fields in microwave ferrite-dielectric waveguiding structures from the given magnetic field distribution of an external source. The solution is derived from the linearized Landau-Lifshits equation using an orthogonality condition for eigenwaves of a magnetization. The magnetization excited in ferrite is obtained in an electrodynamic, magnetostatic or dipole-exchange approximation, depending on the approximation used for eigenwaves. Results are applied for the formulation and the analytical solution of self-consistent electrodynamic problems of an excitation and a reception of waves in ferrite films by transmission lines of an arbitrary type. Numerical calculations are performed for filters and delay lines on the base of symmetric strip-lines using surface and forward volume magnetostatic waves in ferrite films.

The propagation of magnetostatic surface waves in ferrite/superconductor structures

An electrodynamic model that describes the dispersion of magnetostatic surface waves in ferrite/superconductor structures is suggested. On its basis, a new approach to determining the microwave sheet resistance RS of superconducting films in a magnetic field is elaborated. The values calculated (RS=0.20–0.96 mΩ) agree with results obtained by the Tauber method. For YIG/YBCO structures, the controllable phase shift is about 1.5π when the depth of magnetostatic wave penetration into the YBCO film varies from 2.0 to 0.8 µm.

Electronically tunable nondispersive magnetostaticwave delay line

An electronically tunable, nondispersive magnetostatic wave delay line consisting of cascaded magnetostatic backward volume waves and magnetostatic surface waves delay lines has been designed and realised. The distinguishing feature of the device is a wide continuously tunable time delay range of ±30% with the central value of 58 ns. An obtained bandwidth for constant time delay is ~300 MHz at a 3.15 GHz centre frequency. A deviation from constant delay is &lt; ±5%.

High-Speed Nonreciprocal Optical Switching Using Phase Shift Induced by Magnetostatic Surface Waves

Interaction between optical guided waves and magnetostatic waves (MSW) has great potential for wideband optical signal processing directly at microwave signal frequencies. However, till now, all theoretical and experimental investigation has focused on optical mode conversion involving a change in polarization induced by magnetostatic waves. So far, the efficiency of this mode conversion has been low. Here, we propose and analyze, for the first time, the feasibility of obtaining an optical phase shift induced by magnetostatic surface waves in thin film waveguides. We show that with proper selection of the waveguide parameters, it is possible to obtain a phase shift which is sufficient for design of efficient optical-MSW signal processing devices. Further, we propose and analyze a device structure for an optical switch based upon this phase shift and demonstrate the design feasibilty through a numerical example.

Stochastic instability of the magnetostatic surface wave trajectories in a ferrite film magnetized by a modulated field with a banklike profile

We report on the previously unstudied stochastic process arising when a magnetostatic surface wave (MSSW) propagates in a ferrite film magnetized by a modulated periodic inhomogeneous field with a banklike profile. The shape of the MSSW trajectories and the phase portrait of the stochastic process were established. It is shown that the MSSW trajectory becomes unstable and terminates when the MSSW propagation angle exceeds the cutoff angle.

Efficient analysis of magnetostatic surface waves in printed and suspended ferrite loaded strip lines

This paper analyzes the guidance of magnetostatic surface waves (MSSW) by a metallic strip printed on a ferrimagnetic slab or on a dielectric/ferrimagnetic structure (suspended configuration) in the frame of the magnetostatic approach. An integral spectral domain analysis (SDA) is used for this purpose. Shielding upper and/or lower ground planes are also considered. Some interesting new physical effects, such as backward and complex MSSWs in the suspended configuration are reported. Good agreement with previously published experimental and computed results confirms the validity of our approach.

ANALYSIS OF THE EXISTENCE OF MAGNETOSTATIC SOLITONS IN FERROMAGNETIC FILMS UNDER THE INFLUENCE OF CARRIERS

Under the influence of semiconductor carriers, within certain frequencies, along the direction of propagation perpendicular to the external magnetic field, magnetostatic surface wave can develop into magnetostatic solitons, with the group velocity and phase velocity being opposite to each other, and the magnitude of the velocity changes with the carriers density.

Comprehensive analysis of strip- and slot-line guided forward, backward, and complex magnetostatic waves

This paper presents a comprehensive and accurate analysis of the guidance of volume and surface magnetostatic waves by strips or slots in the presence of a ferrite slab magnetized to saturation by an external uniform magnetic field. The strip/slot can be directly printed on the ferrite surface or separated from it by means of a dielectric layer of arbitrary thickness. The problem is posed in terms of a suitable integral equation accounting for the magnetostatic limit. This equation is solved by using a spectral-domain formulation. The proposed method allows for the consideration of arbitrary magnetization angles and the presence of upper and/or lower ground planes. Strip-guided forward, backward, and complex surface magnetostatic waves have been obtained and analyzed in terms of the appropriate waveguide parameters. Slot-guided backward volume magnetostatic waves have been also computed and studied. Theoretical results have been checked against theoretical (magnetostatic and full wave) and experimental data available in the literature with reasonable agreement.

Excitation and Reception of Electromagnetic, Magnetostatic and Spin Waves in Ferrite Films - Abstract

The paper presents a new universal formulation of electromagnetic fields in microwave ferrite-dielectric waveguiding structures from the given magnetic field distribution of an external source. The solution is derived from the linearized Landau-Lifshits equation using an orthogonality condition for eigenwaves of a magnetization. The magnetization excited in ferrite is obtained in an electrodynamic, magnetostatic or dipole-exchange approximation, depending on the approximation used for eigenwaves. Results are applied for the formulation and the analytical solution of self-consistent electrodynamic problems of an excitation and a reception of waves in ferrite films by transmission lines of an arbitrary type. Numerical calculations are performed for filters and delay lines on the base of symmetric strip-lines using surface and forward volume magnetostatic waves in ferrite films.

Bragg Interaction of Surface Magnetostatic Waves with a Periodic Granular High-Temperature Superconducting Structure

Bragg interaction of surface magnetostatic waves with a periodic granular high-temperature superconducting structure is studied. A dispersion equation for coupled waves describing the characteristics of surface magnetostatic waves is derived. Resonance wave absorption near the critical temperature is revealed. The magnetostatic wave reflection coefficients of semi-infinite and finite periodic high-temperature superconducting structures are calculated. The results obtained can be used in designing tunable frequency selectors and transient bolometric photodetectors.

Magnetostatic surface waves on a moving domain boundary in a garnet ferrite crystal

The behavior of magnetostatic surface waves on a domain boundary uniformly propagating in a garnet ferrite crystal was theoretically studied. It was established that the boundary motion, while not affecting the magnetostatic surface wave structure, may significantly modify the wave spectrum.