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A nonlinear spin-wave (magnonic) logic gate based on the ferrite-film Mach-Zehnder interferometer was realized. The gate has two inputs and one output. The principle of operation of the device is based on the power-dependent phase shift of spin waves propagating in an yttrium iron garnet film. A XOR logic functionality for two digital data streams supplied to the gate inputs is shown. No control signal is needed for the gate operation. The performance characteristics of the device are discussed. Reliable functionality in the pulsed regime at 50 and 250 kb/s is demonstrated.

Structural Magnetostrictive Alloys: From Flexible Sensors to Energy Harvesters and Magnetically Controlled Auxetics

We have developed magneto-optic spatial light modulators (MOSLMs) with submicrometer-size magnetic pixels for wide-viewing-angle holographic displays (3-D-MOSLM) that are driven by the thermomagnetic recording. The holographic images were reconstructed by the magnetic hologram pattern on the MOSLM. In this paper, we have studied colorization of reconstruction images of the MOSLMs using optical space division method. This method used some 3-D-MOSLMs to represent intermediate colors. The magnetic films were polycrystalline bismuth, dysprosium, and aluminum substituted yttrium iron garnet (BiDyYFeAlG) films with perpendicular magnetization. The thickness of BiDyYFeAlG films was designed for each wavelength. The MOSLM represented (3-D) images with intermediate colors that were synthesized 3-D images with red and green colors. In addition, tones of intermediate colors were represented by controlling intensity of each reference light. These results demonstrated that 3-D-MOSLMs have promise for full-colorized holographic 3-D displays.

A 128 by 128 magneto-optic spatial light modulator (MOSLM) with single magnetic domain pixels, which is driven by using only drive lines without external bias coil, is described. The array of pixels was formed with Bi substituted iron garnet film grown by liquid phase epitaxial (LPE) method. Since the magnetic switching field of the pixels was so large owing to their growth induced magnetic anisotropy, we reduced it by annealing. Straight copper lines, which have low electrical resistance and enable to apply a homogenous magnetic field to the pixel, were used as drive lines. These improvements reduced an electric power 70% compared with conventional MOSLM and kept the pixels with a single magnetic domain after switching. Though the domain structure depended on the pulse width of current, the frame rate of 5 kHz was estimated by using optimized drive condition.

This paper proposes a vibrational circuit breaker which cuts an electric and/or electronic circuit by vibration of acceleration more than a certain value. This structure consists of a fixed magnet, a moving magnet, and a fixed part of two ferromagnets/magnet. It works from on-state to off-state when the two ferromagnets separate. This vibrational circuit breaker has advantages: auto-detection, no battery, and simple structure.

The vertical deposition technique and the RF-magnetron sputtering method were employed for fabrication of three-dimensional (3-D) magnetophotonic crystals, in which a bismuth-substituted yttrium-iron-garnet planar defect layer was sandwiched in between two opal thin films. Optical properties and structure of constitutive elements (opal thin films) were studied in detail. An evolution of optical response of a magnetophotonic heterostructure under preparation is presented

Magneto-optical (MO) Faraday effect of discrete magnetic media was analyzed theoretically taking the structural randomness into account. The analysis was achieved using the random matrix approach by employing a model with a one-dimensional quasirandom array structure. The numerical results suggest that the MO Faraday spectra (MO-FS) of the discrete media with fine structures are determined uniquely without a significant influence from the structural randomness. In such a medium, the packing density of the magnetic materials and the medium thickness were found to be key parameters which govern the unique MO-FS of the discrete medium.

In order to fabricate the thick ferrite films, electrophoretic deposition (EPD) of Ni-Zn ferrite fine particles in water dispersion mixtures was carried out at room temperature. It is shown that densely packed ferrite films with a thickness of 12/spl mu/m can be deposited via EPD at high deposition rate of 400nm/min from fine particles with a size of 10-30nm onto an ITO glass substrate. The particulate film exhibited soft magnetic properties almost the same as raw particles.

We report results on fabrication of three-dimensional (3D)-magnetophotonic crystals (MPCs) based on artificial opals. The opal samples composed of amorphous SiO/sub 2/ spheres were prepared using gravitational sedimentation. Quantitative evaluation of opal structure was done by fitting the (111) photonic bandgap by a Gaussian function. Changes in depth and width of the (111) photonic bandgap were observed after polishing less-ordered bottom side of the as-grown opal samples. To create 3D-MPCs, terbium gallium garnet was synthesized in an opal matrix.

We demonstrate a magnetooptic spatial light modulator with one-step pattern formation of iron-garnet films on ion-milled substrates by liquid-phase epitaxy (LPE). The one-step pixel growth is acquired by the combination of a single-crystal epitaxial film growth by LPE and an impeded film growth on a substrate whose surface has been locally damaged and milled by ion bombardment before film deposition. The interface between pixel (single-crystal expitaxial area) and pixel gap (perturbed epitaxial area) guides magnetic walls just like a groove. The fabricated prototype magnetooptic spatial light modulator (MOSLM) is switched by applying driving currents of 40 mA for the bottom conductor line and 80 mA for the top conductor line under external bias field of 20 Oe, which is over two times smaller than that of the conventional MOSLM. The novel MOSLM can provide higher resolution, simpler fabrication process, more compact systems, and lower driving current.

Magnetization-induced second-harmonic generation (MSHG) is studied in one-dimensional magnetophotonic crystals formed from a stack of ferromagnetic Bi-substituted yttrium-iron-garnet layers alternating with dielectric films. The resonance enhancement of reflected MSHG due to the phase-mismatch compensation is observed for longitudinal dc-magnetic-field application if the fundamental radiation is tuned across the photonic band gap edge. The high-contrast magnetization-induced variations in the second-harmonic intensity are obtained in transversal configuration of the nonlinear magnetooptical Kerr effect.

Thermal elasticity and electrical resistivity with the magnetic phase transition were studied in FeRh alloy films prepared by ion-beam sputtering and subjected to post-annealing. Fe/sub 49.7/Rh/sub 50.3/ and Fe/sub 48.9/Rh/sub 51.1/ films deposited on conventional glass substrate and subjected to post-annealing at 600/spl deg/C for 90 min, respectively. Both films show a considerably sharp transition. In particular, Fe/sub 49.7/Rh/sub 50.3/ film exhibits small thermal hysteresis of about 20/spl deg/C width, which is only about 2 times over than that of bulk. Furthermore, a large abrupt thermal strain over 2/spl times/10/sup -3/ was observed with the magnetic transition. These results indicate that strictly controlled an equiatomic composition is an effective way to obtain the FeRh film with abrupt magnetic phase transition under low temperature and short time annealing.

To fabricate ferrite films, electrophoretic deposition (EPD) of magnetite fine particles, synthesized by Fe/sup 2+//spl rarr/Fe/sup 3+/ oxidation, in water dispersion mixtures was carried out at room temperature. It is shown that densely packed ferrite films with a thickness of 9.2 /spl mu/m can be deposited via EPD from magnetite fine particles with a size of 10-30 nm onto a copper substrate. The film exhibited soft magnetic properties almost the same as raw magnetite particles.

Summary form only given. Microwave heating is an emerging technology, which uses the ability of some liquids and solids to transform electromagnetic energy into heat. Recently it has been shown that it is possible to produce hematite, magnetite and iron-magnetite nanoparticles by microwave heating of alcoholic solutions of a ferrous salt. The developed original microwave applicator associated with autoclave for one flash synthesis of nanoparticles by disproportionation of ferrous alcoholic solutions as well as operation conditions is described elsewhere Caillot et al. (Journ. of Mat. Sci. (2002)). We present the results of experimental study of magnetic and structural properties of magnetic nanoparticles fabricated by this technique. Comparing with similar nanoparticles fabricated by using a conventional heating, we obtained much lower grain size (up to 10 nm) and very stable properties. The hysteresis loop for samples of the non-oriented assembly of hematite particles has a coercive force about 100 Oe with squareness about 0.4. Some quantity of superparamagnetic fraction exists in our sample. The particles distribution on the anisotropy fields has a maximum about 200 Oe. The possibility of improvement of the magnetic properties is under investigation.

A one-dimensional (1-D) magnetophotonic crystal (MPC) film made of a magneto-optical layer with nonmagnetic layers laminated thereon has an enhanced Faraday rotation. Theoretical studies about 1-D MPC films for use in magneto-optical (MO) applications of optical communication were carried out. The calculations revealed that required optical isolator performance (transmittance T>95% and Faraday rotation angle /spl theta//sub F/=45/spl deg/) can be fulfilled with the periodic multilayer films having only two or three magnetic layers. The structure of 1-D MPC films satisfying the optical isolator performance is very simple, which is very attractive for actual optical isolator fabrication.

A magnetic micro-machine, a minuscule device composed of a cylindrical body with a magnet and spiral blade, swims in liquid under the force of a rotational magnetic field. To obtain a machine capable of swimming through organs and blood vessels for medical applications, it must be designed on a scale below the mm order and retain its swimming capability under highly varied conditions. The swimming properties of a spiral-type magnetic micro-machine were examined under various Reynolds number conditions by altering the kinematic viscosity of the liquid. The machine could swim in liquids with kinematic viscosities ranging from 1.37 to 5/spl times/10/sup 5/ mm/sup 2//s, which translates into a Reynolds number from 430 to 6/spl times/10/sup -7/. The Reynolds number of blood flow is within this range. In addition, the load torque for swimming was studied theoretically and experimentally. The results obtained suggested great promise for the development of a micro-machine that can be put to work inside the human body.

The magnetic properties of Fe-based amorphous films are thought to be highly sensitive to strain due to the large saturation magnetostriction and soft magnetic properties exhibited by the films. This is why patterned FeCoSiB films exhibit a large variation in their high-frequency impedance when strain is applied. To increase the sensitivity of strain sensors, it is very important to control the magnitude of magnetic anisotropy. We propose a method to control the magnetic anisotropy by stress bias annealing. By applying stress during annealing, we were able to control the anisotropy along the width of the patterned film. A strain sensor using a transverse-anisotropy-induced film pattern exhibited a figure of merit F/spl ap/8300, while a sensor without anisotropy exhibited F of only 500.

A remote temperature sensing system was investigated. The system can measure the temperature by applying an external magnetic flux to the sensor and by receiving a flux at the resonant frequency corresponding to the temperature at the sensor. The sensor does not need a power supply within it and is only composed of a temperature sensitive ferrite core and a wound coil. The inductance of the core varied from about 8-18 mH in the temperature region of 35-55/spl deg/C. The induced voltage, /spl Delta/V by the sensor was about 10 mV for a 260 mm length between the transmitter and receiver. The system was successfully operated in our investigation.

Tunneling magnetoresistance of granular Co-Ta-O films sputtered under an obliquely arranged electrodes was investigated as a function of the film thickness and the concentration of Co to Ta/sub 2/O/sub 5/. Formation of micro-scale structures such as corrugated surface elongating perpendicular to the incident ion-beam (thickness 50 nm) were quite similar to vacuum evaporated films, As a result of these structures, the resistivity at zero field /spl rho/(0) and the resistivity change with field /spl Delta//spl rho/ became about 1 order of magnitude larger compared to those of films sputtered under ordinary parallel electrode arrangement.

A theory for analyzing the flap motion of wings of small flying elements driven by an alternating magnetic field was developed. The elements have the combined wings which are composed of magnetic and polyimide sheets connected with hinges. Motion equations of wings were obtained by examining the losses of flap motion of wings in detail. They were solved numerically, and the results were studied with experimental ones. The analytical results coincide very well with the experimental ones: the difference between the theoretical and experimental results was evaluated to be less than 17/spl deg/ in terms of the elevation angle of wings. This suggests that the theory developed here is useful for determining the motion of wings and hence for designing the elements with optimal structures for flying.

To improve the low field magnetostrictive response of TbFe sputtered films, the effects of slow rate and rapid rate thermal annealing on the magnetic and magnetoelastic properties of the films were investigated. The annealing was achieved for amorphous TbFe films with the composition around 40 at.% Tb, because these films simultaneously exhibit relatively soft inplane magnetization and considerably large magnetostriction. The present work shows that thermal annealing is very effective for improving the low field magnetostrictive response of a film, for example, the engineering magnetostriction of amorphous Tb/sub 40/Fe/sub 60/ film at 500 Oe became 5.1 times larger by annealing from 46/spl times/10/sup -6/ to 235/spl times/10/sup -6/.

The propagation properties of Love-type magneto-surface acoustic waves (MSAW) in FeB/SiO/sub x/ multilayers (0.5 /spl mu/m/spl times/10) have been studied. The insertion loss of MSAW devices was found to vary with the applied field strength and orientation angle in an approximately periodic fashion. When the acoustic aperture was restricted to a narrow strip along the center line of a square magnetic film (1 cm/spl times/1 cm), the oscillations of the insertion loss were greatly reduced. Calculation of the demagnetizing field showed that the resultant inhomogeneity of the internal field can produce the delay difference of the partial waves up to 1.5-2 wavelengths (/spl lambda/=36 /spl mu/m), and cause their interference at the output transducer.

The magneto-optical Faraday effect in discontinuous magnetic media was analyzed by employing the matrix approach method. The discontinuous media have a one-dimensional array structure composed of magnetic materials (width D/sub M/) and air gaps (width D/sub G/) which are aligned alternately. The analysis reveals that, when the medium meets the condition of D/sub M/

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.