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Magnetics in Japan, IEEE Translation Journal on

Issue 2 • Date March-April 1994

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Displaying Results 1 - 25 of 32
  • [Front cover]

    Page(s): c1
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  • List of contributors

    Page(s): nil1
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  • [Breaker page]

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  • Table of contents

    Page(s): 1 - 2
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  • High-Frequency Permeability of Composite Anisotropic Multilayers

    Page(s): 3 - 8
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    We have investigated a double-structured four-layered composite anisotropic film with the aim of obtaining advanced properties for practical use. The film composition was {[CoNbZr(250 nm)/SiO2(20 nm)]4/ SiO2(t)}4, with a shift angle of 45°. The sample was annealed in a weak rotating miagnetic field. The total thickness of the metal layers was 4.0 ¿m, with an optimum SiO2 thickness. The film permeability showed a flat frequency response and small temperature coefficient. A larger SiO2 layer thickness is recommended for applications. Annealing at between 200°C and 400°C resulted in a high permeability in the range of 1000 to 2000 and an excellent frequency response of ¿' at 1 to 100 MHz in all directions within the film plane. These results may be explained in terms of the magnetic interactions of the CoNbZr magnetic layers, which are in close contact with one another through the intervening SiO2 layers. View full abstract»

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  • Soft Magnetic Properties of FeCo/Zr Multilayers

    Page(s): 9 - 16
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    The soft magnetic properties of Fe100¿xCox (x=30 or 4) multilayer (ML) films prepared by rf magnetron sputtering are reported. The growth of FeCo crystallites is suppressed by the presence of Zr intermediate layers, and the layer structure is stable up to 500°C. The annealing behavior of the coercivity and permeability is discussed in relation to the magnetostriction and magnetocrystalline anisotropy of FeCo crystallites. View full abstract»

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  • Soft Magnetic Properties of High-Resistive CoBN/AIN Multilayers

    Page(s): 17 - 24
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    The magnetic and structural properties of multilayered CoBN/AIN films prepared by sputtering were investigated with the intention of creating film suitable for application in micromagnetic devices operating at high frequencies. A CoBN single-layer film has a resistivity ¿ of about 340 ¿¿-cm, a Bs of about 10.3 kG, and perpendicular magnetic anisotropy. CoBN/AIN multilayer films, even when the AIN layer thickness is about 3Å, exhibit soft magnetic properties (Hc≪1 Oe and ¿≫500) for a variety of layer thickness combinations. SEM observations suggest that the soft magnetic properties of the multilayer films originate in their in-plane uniaxial anisotropy and in the fine grains in the CoBN layers. The magnetostriction of multilayer films ranged between ±1×10-6, and the anisotropy field was over 15 Oe. Although film thicknesses exceeded 2 ¿m, a high permeability ¿ was maintained, even at frequencies close to 300 MHz. View full abstract»

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  • Study of Electron Beam Trajectory within CRTs Containing U-Shaped Magnetic Sheets

    Page(s): 25 - 30
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    This paper proposes a new method for shielding the ambient magnetic field in a CRT. The key to the method is the use of U-shaped magnetic sheets arranged around the frame of the CRT. The sheets are magnetized by the ambient field, and create a demagnetizing field to cancel the field perpendicular to the screen. They are thus an effective means of reducing mislanding. For example, mislandings at the corner of the screen were reduced to one-fourth of the number that occurred without the sheets. On the other hand, the sheets have no shielding effect on the field parallel to the screen. View full abstract»

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  • On the Air Gap Flux-Density Distribution and Characteristics of Linear Parametric Motors

    Page(s): 31 - 35
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    The structure and operation of a four-legged linear parametric motor include such excellent features as a very simple construction and negligible operating maintenance. We calculated the performance characteristics of such linear motors numerically, using a two-dimensional static field analysis program, and obtained the flux density distribution in the gap. We here show that the performance characteristics of four-legged linear parametric motors can be improved by decreasing the thickness at the center of the common magnetic circuit. View full abstract»

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  • Experimental Studies on Iron Loss in a Parametric Motor

    Page(s): 36 - 42
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    Parametric motors offer numerous attractive features not found in ordinary motors, such as overload protection, simple construction, low cost, and low noise. This paper discusses the mechanism of iron losses occurring in the cores of a parametric motor, with a view to further improving the motor's characteristics and putting it to practical use. It is shown that the greater part of the iron loss in the motor occurs in the common magnetic circuit, and is caused by an alternating magnetic flux in a direction perpendicular to the plane of the lamination. It is also shown that the eddy current loss occurring in the common magnetic circuit when the latter is radially excited is closely related to the magnetization process due to domain wall displacement. View full abstract»

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  • Resonance Analysis of a Permeance Meter Using a Figure-of-Eight Coil

    Page(s): 43 - 48
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    We derived an equivalent circuit for a figure-8 coil type permeance meter in order to analyze its LC resonance characteristics. The equivalent circuit for the pickup coils was derived by using the same analytical techniques as for thin-film inductors. The driving sheets and twisted lead wires were modeled according to the theory of distributed constant networks. We made a permeance meter, measured the frequency characteristics of the impedance for the coils, and confirmed the validity of the equivalent circuit. After describing the above steps, we discuss the LC resonance caused by the stray capacitance between the pickup coils and the driving sheets. View full abstract»

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  • Film Thickness Dependence of Coercivity in Obliquely Vacuum Deposited Co-Cr Films

    Page(s): 49 - 55
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    The film thickness dependence of the coercivity in obliquely vacuum-deposited Co-Cr films and Co films was studied. A coercivity of 80 kA/m was obtained for Co-Cr films obliquely deposited at a substrate temperature of 80°C. The coercivity of obliquely deposited Co-Cr films was larger than the values of obliquely deposited Co films and normally deposited Co-Cr films. The high coercivity of obliquely deposited Co-Cr films seems to be induced by both the self-shadowing effect and by segregation of Cr at grain boundaries. We estimate that about 1/3 of the Cr atoms in the film samples were segregated. View full abstract»

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  • Structure and Tribological Characteristics of DC-Magnetron Sputtered DLC Overlayer Films

    Page(s): 56 - 62
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    We investigated the structure xand tribological properties of diamond-like carbon (DLC) overcoat films for rigid magnetic disks. DLC films were produced by DC magnetron sputtering, introducing CH4 gas into Ar gas in various quantities. Drag tests and CSS tests were performed, and the electrical resistivity, Raman spectra and film hydrogen contents were measured. A more polymer-like DLC film appeared to have good tribological properties, making it suitable as a hard-head slider material (Al2O3-TiC). View full abstract»

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  • Investigation of Magnetic Recording Media with Magnetic Layer Divided by Cr Interlayer

    Page(s): 63 - 69
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    The magnetic properties and recording characteristics of magnetic recording media with the magnetic layer divided by a Cr interlayer (i.e. a multilayered medium) have been investigated. A reduction of media noise and improvement in SNR were observed. At an interlayer thickness of 3 nm, the SNR was higher than that of CoCrTa singlelayered media. If the interlayer thickness is greater than 3 nm, the overwrite level is lower than for single-layered media. When the thicknesses of the two magnetic layers are equal, the multilayered medium offers good recording characteristics. View full abstract»

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  • High Resolution Hard-Disk Media for Perpendicular Magnetic Recording

    Page(s): 70 - 77
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    While the main pole of single-pole type heads must be kept thin to improve the high linear density response in perpendicular magnetic recording, the magnetic interaction between the main pole and the backing layer of the double-layered media is weakened as a result. The experimental results of this study show that double-layered media with a thin Co-Cr recording layer intensifies the magnetic interaction, so that the linear density response is improved. In addition, ferrite-substrate disks were investigated for possible use in high-frequency applications, as a means of achieving high linear densities and high data rate recording. View full abstract»

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  • Magnet-Displacement Sensor Using Magneto-Inductive Elements for Sensing Eyelid Movement

    Page(s): 78 - 83
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    We previously constructed an accurate displacement sensor for detection of eyelid movement, using an amorphous magnetic core multivibrator. Improvements in eyelid motion sensors are necessary to achieve independence of the magnetization direction of the cores as well as a broadened visual field. We constructed a second displacement sensor for detection of eyelid movement, this time using amorphous wire magneto-inductive (MI) elements. The elements were formed from tension-annealed zero-magnetostriction amorphous wires. The MI effect and the symmetrical MI characteristics of the elements were used to form thin sensor heads without coils. Inductances change independently of the magnet magnetization directions. View full abstract»

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  • Magneto-Inductive Effect in Amorphous Wires and MI Elements

    Page(s): 84 - 91
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    In the magneto-inductive effect (MI effect), the inductance L of a ferromagnetic wire element magnetized by an ac current Iac in the wire is changed by an external magnetic field Hex. When the current Iac is passed through the wire, a voltage etot is induced across the wire ends. The voltage has two components: a voltage eR due to RwIac (where Rw is the electrical resistance of the wire), and a voltage eL equal to d¿¿/dt (where ¿¿ is the circumferential flux in the wire cross-section). eL is detected by subtracting eR from etot using a simple resistor circuit. The amplitude |eL| of eL decreases with decreases in L caused by increases in |Hex|. That is, eL is amplitude-modulated by |Hex|. The waveform of |Hex| is detected using a simple demodulator based on a diode and capacitor. A sensitive MI element is created by using a slightly negative magnetostrictive amorphous wire of length 2 mm and diameter 50 ¿m, without a coil. This MI element is expected to find applications in sensitive magnetic heads for accurate rotary encoders, in rigid disk drives, and in various magnetic cards. View full abstract»

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  • Construction of Pressure and Photo Sensors Using Ferrite Thick Films

    Page(s): 92 - 96
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    This paper describes the preparation of ferrite thick films (FTFs) and their application to pressure and photo sensors. The FTFs are composed of ferrite powder with various Curie temperatures, polymers and solvents. A magnetic semiconductor fluid mixture was dried at 120°C after printing onto a plastic substrate. A pressure sensor was constructed using a high-Curie temperature FTF and a pressure-sensitive element. The FTF converts pressure into reluctance, and a Hall element reads out small changes in flux as the pressure and reluctance vary. When a photosensing PFTF, which is a low-Curie temperature FTF coated with a radiant flux absorbent, absorbs light energy, the PFTF reluctance increases, effecting an optomagnetic conversion. Thus FTFs can be used for measurement of pressure, position, fluid flow, and luminance. View full abstract»

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  • Characteristics of an Amorphous Alloy Layer Prepared by Laser-Quenching, and Its Application to a Torque Sensor

    Page(s): 97 - 101
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    An amorphous alloy layer prepared by a laser-quenching technique was employed in the construction of a magnetostrictive torque sensor. Fe78B13Si9 amorphous alloy layers were produced on stainless steel substrates by laser-quenching. The laser-quenched layers consisted of a mainly amorphous phase, partially including regions crystallized under the influence of heat (heat-affected zones). VSM measurements showed that the amorphous alloy layers have an axis of easy magnetization in the laser scanning direction. Taking account of this magnetic anisotropy, we prepared a torque sensor by scanning a laser beam over the shaft surface at 45° to the shaft axis. The torque sensor thus prepared exhibited sufficient sensitivity and good linearity in detecting static torque. View full abstract»

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  • Distance Sensors Utilizing a Current-Exciting Large Barkhausen Effect in Twisted Amorphous Magnetostrictive Wires

    Page(s): 102 - 108
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    A distance sensor which uses the large Barkhausen effect in amorphous wires magnetized by a current is described. A helical anisotropy is created in an Fe77.5Si7.5B15 amorphous wire (cold-drawn and then tension-annealed) by applying torsion, and consequently the wire can be magnetized by the circumferential magnetic field created by the wire current. This type of distance sensor does not require a long exciting solenoid coil, and its construction is simple. The characteristics of the sensor are controlled by the number of turns used to apply the torsion. The smallest deviation from linearity, ¿=0.4%/FS for a 1000 mm long wire, was obtained when the torsion was 10 turns/m. Domain wall motion in a twisted amorphous wire was also analyzed. The domain wall velocity increases linearly with the wire current, and its mobility decreases with increasing torsion. View full abstract»

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  • Soft Magnetic Properties of Fe-N Films Composed of Two Phases

    Page(s): 109 - 115
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    Fe-N films were synthesized by means of ion beam deposition. Nitridation was performed using an assist gun during the sputtering of Fe films. The as-deposited Fe-N films consisted of two phases, ¿-Fe and ¿'-Fe4N, and had a high coercive force Hc of over 20 Oe. When the films were annealed in vacuum, their Hc improved drastically, and had a minimum value of less than 1 Oe at 400°C. The films also had a high permeability of over 2000 as well as high resistivity (around 80 ¿¿-cm), in spite of a high saturation magnetization (around 18 kG). The small grain size and stress relaxation in the films are closely related to the soft magnetic properties. The volume fraction of the ¿'-Fe4N phase also affected the decrease in Hc, because the anisotropy normal to the film plane is reduced by increasing the magnetostatic energy when the volume fraction was 0.5. View full abstract»

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  • Thrust Analysis of the Linear Proportional Solenoid for a Hydraulic Control Valve

    Page(s): 116 - 123
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    The linear proportional solenoid (LPS) is an actuator for a proportional control valve used in hydraulic pressure-control devices. The LPS must have a constant thrust over a designated displacement range, and the thrust must also increase in proportion to the exciting current. This paper deals with the effect of using dither to remove hysteresis phenomena, and describes numerical solutions for the thrust F and displacement x, which are characteristics of the LPS. Dither is a useful small-amplitude oscillation which is introduced to overcome the effect of hysteresis. When dither is applied, the maximum hysteresis of the thrust is decreased from 6% to 3%. The LPS consists of four different magnetic materials, and its F-x characteristic was calculated by the finite element method (FEM). The calculated F-x characteristics approximated the measured results to within an error of 2%. A newly proposed LPS, which maintains constant thrust over a broader range, is also described. View full abstract»

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  • A Study of the High-Frequency Magnetic Properties of CoZrNb/SiO2 Multilayer Films

    Page(s): 124 - 129
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    This paper reports on the design of a magnetic multilayer film with high permeability and low loss in the 1 MHz to 1 GHz range. The thickness of each layer and the magnetic anisotropy were optimized with respect to the eddy current loss and ferromagnetic resonance in the magnetic layers, and with respect to the dielectric breakdown in the nonmagnetic insulating layers. A limit relation for the product of permeability ¿'r(0) and the cutoff frequency fc was analyzed. The limit ¿'r(0)xfc is expected to have a much higher value than Snoek's limit. A value for ¿'r of 300 was achieved in the range from 1 MHz to 1 GHz in an optimized CoZrNb/SiO2 multilayer film. View full abstract»

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  • Structure and Characteristics of the Cordless Power Station

    Page(s): 130 - 134
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    The "Cordless Power Station" is a power supply system which does not use cords. The system makes use of electromagnetic induction generated with coils. Such systems will have uses such as supplying power to portable household electrical appliances or charging the batteries of circuits. We studied the power-transmitting characteristics and structure of a cordless power station. We also describe measurements of the distribution of the magnetic flux density around the coils, and discuss the effects of using amorphous fiber. View full abstract»

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  • Analysis of a Hysteresis Motor on Asynchronous Speed Using Complex Permeability

    Page(s): 135 - 142
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    This paper deals with a method for determining the complex permeability in analysis of hysteresis motors. The method assumes that the magnetic intensity distribution is sinusoidal in the direction of rotation. Analysis of the asynchronous speed of a hysteresis motor is then performed for cylindrical coordinates, using modified Bessel functions. The results of calculations are in good agreement with experimental results, confirming the effectiveness of the proposed model and method for determining the complex permeability. View full abstract»

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Aims & Scope

IEEE Translation Journal on Magnetics in Japan is a publication of the IEEE Magnetics Society published between 1985 and 1994.

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Editor-in-Chief
James E. Opfer
Hewlett-Packard