Search

A convenient measurement of the magnetooptic Faraday spectra, i.e., the Faraday rotation angle θ F and Faraday ellipticity χ F vs wavelength, is presented based on ellipsometry in which the polarizer and analyzer are set in an off-crossed polarization state. This system is suitable for full computerization, enabling us to achieve efficiency in measurement without loss of accuracy. A very good agreement of the spectra between the present method and an ordinary crossed polarization method was found using a bismuth-substituted yttrirnm-iron-garnet film.

A computer-controlled laser probe surface-acoustic-wave (SAW) observation system was constructed, which facilitates reconstruction of 3-dimensional images of travelling Rayleigh SAWs. Vivid images of a propagating single SAW and two colliding SAWs on a glass plate were observed by this system. The system is thus used as a powerful tool for elucidating the dynamic behaviors of SAW, especially for identification of surface acoustic solitons.

We have constructed Love-type magneto-surface-acoustic-wave (MSAW) devices using amorphous FeB alloy films sputtered on glass substrates. For the Love-type SAW transducers, we employed interdigital electrodes combined with ZnO films rf-sputtered by oblique deposition, where the crystallographic c-axis of ZnO film is grown inclined to the substrate plane. The velocity controllability of a device using monolayer FeB film (operated at 72 MHz) is 1.03%. This controllability can be improved through the suppression of eddy-current accompanying MSAW propagation using multilayer FeB films alternately stacked with thin SiO x layers.

In the construction of excellent magneto-surface-acoustic-wave (MSAW) devices utilizing magnetostrictive films, MSAW media must satisfy two contradictory requirements of large magnetostriction and high magnetic permeability simultaneously to ensure large magneto-mechanical coupling. For this purpose, hydrogen mixing in argon sputtering gas is found to be effective to improve magnetic properties in rf-sputtered amorphous Fe–B films. Preliminary results of MSAW characteristics fabricated by this method are also described.

A new technique for sequential SIMS-ISS measurements was developed using the double focusing mass spectrometer of a SIMS instrument operated with a B2 / E linked scanning method and a modulation technique. Formulations that give the scattered ion energy and the mass resolution were also derived in the biased sample condition. The energy resolution of this system was assessed at nearly 40 with an ISS spectrum obtained from a GaAs monocrystal surface.

The ion-induced photon emission from excited Ga atoms sputtered from a GaAs single crystal was measured as a function of cesium coverage on the specimen surface. The results showed a remarkable non-linearity in photon yield against cesium coverage. This implies that the photon enhancement effect due to cesium adsorption is nonlocal and relates to the nonradiative deexcitation process of sputtered atoms.

Propagation properties of fundamental magnetoelastic waves (MEWs) in a highly magnetostrictive slab have been studied. Analysis and experiment show that there exist three fundamental MEWs: Lamb extensional-type, Lamb flexural-type and SH-type MEWseven in a single homogeneous magnetic slab. The results reveal that the propagation properties of MEWs are determined by not only the magnetic parameters such as the magnetoelastic coupling constant but also by the geometrical ratio of the thickness to the drive frequency. The analysis suggests that in order to realize large velocity change in MEWs with a small field the easy axis direction should be changed according to whether the Lamb-type or the SH-type MEW is used. The SH-type MEW exhibits distinct frequency dispersion which is not observed in the elastic SH-wave in a non-magnetic slab.

The spin structure of an isolated planar 180° -domain wall in magnetic bubble films has been analysed by precise consideration of the magnetostatic energies due to surface and volume charges. The twisted spin configuration inside the wall depends on the ratio of the wall width to the film thickness, Δ/D, and this is substantially different from the approximate treatment developed by Slonczewski.

Magnetoelastic waves (MEWs) propagating in a thin conductive magnetostrictive slab were investigated theoretically taking account of the micro-eddy current contribution. The analysis was performed under the assumption that the medium is amorphous (isotropic elasticity) but has a uniaxial magnetic anisotropy in the slab plane. MEWs in this configuration are three fundamental modes: Lamb-type wave of the extensional mode (EMEW), SH-type wave (SMEW) and Lamb-type wave of the flexural mode (FMEW). The microeddy current crucially affected the propagation properties, thereby increasing the propagation loss as well as decreasing the controllable MEW velocity with external magnetic field. The amounts of these quantities also varied depending strongly on the anisotropy orientation β for the above three wave modes, because the degree of coupling between the magnetization and the lattice through magnetoelastic interaction is different in each mode. The present analysis revealed that SMEW with β=45° is the most favorable for delay line application.

The magnetoelastic coupling constant B , or the saturation magnetostrictive constant λ s in highly magnetostrictive amorphous ribbons was evaluated indirectly from the change of the sound velocity under application of external field or uniaxial tensile strain by comparing with the theory based upon the one-dimensional elastic beam model.

we present an investigation on local properties of magneto-surface-acoustic-waves (MSAWs) propagating on Fe-Co-B amorphous sputtered films supported on soft glass substrates. The local detection of MSAW was performed by means of a light-probing technique based on the principle of Raman-Nath diffraction. The mode of MSAW in the elements was confirmed to be Rayleigh(P+SV)-type and the amplitude of MSAW was subjected to large change from place to place by applying a small field. The attenuation constant of MSAW also varied depending strongly, not only on the field strength, but also on the direction of the field relative to the direction of MSAW propagation. Theoretical analysis explains the experimental results very well in terms of the change of micro-eddy current loss in the conductive magnetic film, which reflects the change in the degree of magnetoelastic coupling in the film with external magnetic field.

The propagation characteristics of magnetoelastic surface waves in a magnetic layer on a nonpiezoelectric substrate are analyzed taking account of both thicknesses of the magnetic layer and the substrate Three fundamental modes of waves propagate in this layered structure; the extensional and the flexural modes of (P+SV)-wave and SH-wave. In these waves, the largest velocity change with external applied field appears in the flexural mode of (P+SV)-wave. The analysis reveals that the maximum velocity change has approximate squared dependence of the ratio of the magnetic layer thickness to the substrate thickness. In addition, in order to obtain large velocity change, magnetic materials are required to possess two extreme magnetic properties at the same time - very soft magnetism and very high magnetostriction.

The theory of a magnetoelastic wave propagating in a magnetic slab with a uniaxial in-plane anisotropy is developed in order to explore the possibility of rf-magnetoacoustic devices. This is regarded as an extension of the theory of the Lamb wave in an elastic slab. Analysis suggests that the magnetoelastic surface wave is advantageous for some applications.

The mechanism and the dynamic properties of the dynamic diffuse wall observed in Garnet bubbles have been analyzed based on two dimensional twist wall with a finite film thickness. The analysis reveals that during wall motion, 360 °‐spin twist nucleates inside the wall and propagates along the film thickness. The wall distortion takes place where the 360 °‐twist appears. Annihilation and/or accumulation of the 360 °‐twist occurs at the film surface. The number of the 360 °‐twists contained in a wall increases with increasing drive and in‐plane fields, which leads to an increase of the apparent wall width obtained by domain walls observed by transmitted light (Faraday effect). Most of the experimental results may be well interpreted by the present analysis.

We present theoretical investigation of two-dimensional (2D) magnetophotonic crystal (MPC) with square lattice constructed from two infinite arrays of magnetoactive dielectric sheets at right angle, in the limit of very small sheet thickness and very high dielectric constant, such that their product is constant. Alteration of band structure by external magnetic field is studied. We show that optical activity reduces symmetry of the system and removes degeneracy in the photonic band structure. Also, despite of natural weakness of the magnetooptic activity, dispersion near band edges is found to be strongly sensitive to external magnetic influence.

We demonstrate that microscale tailoring of surfaces of magnetophotonic crystals provides an approach to engineer responses of known materials. In particular, we study states that are spatially localized at the interface between magnetophotonic and photonic crystals. Such states are an optical analog of the Tamm states long known in solid-state physics. The optical Tamm states are spectrally located inside band gaps and are associated with a sharp transmission peak in spectra of the system. Substantial enhancement of the Faraday rotation for the wavelength of the optical Tamm state is experimentally observed and attributed to strong light coupling to magnetic constituents of the magnetophotonic crystal. The experimental results are in excellent agreement with the theoretical predictions.

3D and 1D magnetophotonic crystals based on opals impregnated by Bi-substituted iron-yttrium garnet (Bi:YIG) and Bi:YIG-SiO 2 paired multilayer structures are fabricated. Magnetization-induced effect (nonlinear magneto-optical Kerr effect) in secondand third-harmonic generation is observed.

Summary form only given. We propose an automatic power controller for an artificial sphincter utilizing a temperature sensitive ferrite core. The sphincter consists of a shape-memory alloy and electric wires. It needs electric power of almost 6-10 W. Temperature control inside the body is necessary in order to protect the tissues from thermal damage. The automatic power controller requires no power, but does require little control circuits for temperature control. An all-in-one design is possible.

We demonstrate the existence of a spectrally narrow localized surface state, the so-called optical Tamm state, at the interface between one-dimensional magnetophotonic and nonmagnetic photonic crystals. The state is spectrally located inside the photonic band gaps of each of the photonic crystals comprising this magnetophotonic structure. This state is associated with a sharp transmission peak through the sample and is responsible for the substantial enhancement of the Faraday rotation for the corresponding wavelength. The experimental results are in excellent agreement with the theoretical predictions.

Propagation properties of magneto-surface-acoustic-waves (MSAWs) in highly magnetostrictive alloy films formed on glass substrates are analyzed using the “matrix approach”. The analysis reveals that MSAWs appearing in this configuration are two modes of the Rayleigh-type and the Love-type SAWs. The velocity and attenuation of these two modes of waves versus drive frequency vary in a different manner depending strongly on the easy axis orientation of the uniaxial magnetic anisotropy in the film plane, which reflects the fact that the coupling between the spin and the elastic system is different.

BGS-type magneto-surface-acoustic-wave(MSAW) devices were constructed by depositing highly magnetostrictive amorphous Fe-Co-B ternary alloy films by RF-sputtering on horizontally polarized PZT-substrates, since this type of MSAW is expected from our theory to have wide controllability of the propagation properties with externally applied magnetic field in comparison with those of the Rayleigh-type MSAW. We measured changes of attenuation and phase velocity as a function of magnetic field, and the results agree qualitatively with those obtained by the theoretical analysis.

Magneto-surface-acoustic-wave (MSAW) devices with three-layer structure were constructed by RF-sputtering, where a thin insulating SiO2 interlayer was sandwiched between two magnetostrictive amorphous Fe–B films of equal thickness. This was based on our previous study which predicted that such multilayered devices are useful to improve MSAW properties since they reduce eddy-current losses in alloy films. More than a 12 dB/cm loss reduction was achieved at the operating frequency of 52 MHz in comparision with single layer devices of the same thickness. The total thickness of magnetic films was found to be a significant parameter in determining the MSAW properties in multilayered devices.

Propagation properties of the Rayleigh-type magneto-surface-acoustic-wave in multilayered magnetic alloy films were studied theoretically, where the films consisted of highly magnetostrictive layers separated by insulating layers. The analysis revealed that multilayer structure is very effective for improvement of magneto-acoustic quantities by reducing micro-eddy-current losses. We further found that the key factor in obtaining optimal conditions in the layered structure is total thickness of the insulating layers (=number of the layers × thickness of the individual layer).

We investigated the magneto-acoustic excitation properties of amorphous iron-boron films prepared by rf-high rate sputtering by observing magnetoelastic wave resonance in linear samples. The longitudinal complex susceptibility was measured as a function of the external applied field. Films about 10 µm thick were deposited onto aluminum foil substrates. The observed magnetoelastic wave was a standing wave of the lowest mode. The controllable change in the velocity of sound by the application of an external field ΔC/C was about 4.7% for films with substrates. This value increased to 17% when films were removed from the substrate, the new value being comparable to that obtained in rapid-quenched Fe80B20 ribbons. The experimental results are explained very well by the one-dimensional string model, from which important magneto-acoustic quantities are derived.