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Volume 16, Issue 3
Displaying 1-12 of 12 articles from this issue
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Papers
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H. Murata, H. Kogure, K. Ichikawa, T. Shinohara1992 Volume 16 Issue 3 Pages 541-546
Published: June 01, 1992
Released on J-STAGE: January 11, 2013
JOURNAL OPEN ACCESSHigh density recording requires longitudinal magnetic recording media with high coercivity and low noise. We report our studies of magnetic and microstructural properties of high coercivity CoCrTa films. A coercivity value of 2450 Oe was obtained applying high bias voltage for substrate. Microstructural analysis by TEM and electron diffraction method revealed that high coercivity film shows c-axis of the film is highly oriented in the film plane.View full abstractDownload PDF (1313K) -
X. Y. Yu, S. Tsunashima, S. Uchiyama1992 Volume 16 Issue 3 Pages 547-550
Published: June 01, 1992
Released on J-STAGE: January 11, 2013
JOURNAL OPEN ACCESSMagnetic and magneto-optic properties were investigated for GdNd/FeCo multilayers prepared by means of RF magnetron sputtering. Adjusting the bilayer period as well as the composition of each layer, perpendicularly magnetized films with a square Kerr hysteresis loop were obtained. The perpendicular magnetic anisotropy increases with decreasing bilayer period. For a composition of 13 at% Co in FeCo layer, the anisotropy shows a maximum of 3×106 erg/cm3 at a bilayer period of 5Å. With increasing Co concentration up to 33 at%, the Curie temperature and the Kerr rotation increase, while the anisotropy shows a maximum at a composition of 10 at% Co. The Kerr rotation increases about 10% at a wavelength of 400 nm compared with GdNd/Fe multilayers. From these results, GdNd/FeCo multilayers are expected to be a candidate for magneto-optical recording media working with blue laser.View full abstractDownload PDF (200K) -
Analysis for Domain Dynamics in Amorphous Magnetostrictive Wires of the Composition (Fe77.5Si7.5B15)L. V. Panina, H. Katoh, M. Mizutani, K. Mohri1992 Volume 16 Issue 3 Pages 551-555
Published: June 01, 1992
Released on J-STAGE: January 11, 2013
JOURNAL OPEN ACCESSDomain wall processes (domain wall configuration, propagation and collapse) in magnetostrictive amorphous wires of the composition (Fe77.5Si7.5B15) were invesitaged. The wires were held under tensile stress (up to 1700 MPa in the case of as-quenched). The domain wall length and normal mobility (or damping) as functions of applied stress were found experimentally and theoretically from an ellipsoidal domain model. This allows the losses to be separated into eddy current and spin relaxation contributions. It was demonstrated that the process of domain collapse affected by internal magnetic field generated a very sharp voltage pulse. The change in the voltage pulse shape with increase of tension was investigated as well.View full abstractDownload PDF (267K) -
T. Uchiyama, M. Makino, K. Mohri1992 Volume 16 Issue 3 Pages 556-559
Published: June 01, 1992
Released on J-STAGE: January 11, 2013
JOURNAL OPEN ACCESSA transistor logic memory module based on the Royer oscillator type magnetic multivibrator is presented, in which a HTcSC thin disk core having six coils tightly set around it is connected with two switching transistors. The oscillation of this module is initiated by applying a pulse current to a coil and the phase of oscillation is controlled by the sign of the trigger pulse. That is, this module is a phase memory type logic device such as Parametron. Moreover, oscillation is terminated by applying a pulse current to a small transistor which shorts another coil of the HTcSC. We can assign two oscillating states with different phases to the numerical values ±1 and the non-oscillating state to 0. This logic is decided by a majority of multi-input, so that this module has applications in the field of neural network system.View full abstractDownload PDF (259K) -
K. Kawashima, T. Kohsawa, M. Takagi, K. Mohri, M. Kanoh, L. V. Panina1992 Volume 16 Issue 3 Pages 560-565
Published: June 01, 1992
Released on J-STAGE: January 11, 2013
JOURNAL OPEN ACCESSMechanism of sensitive Matteucci effect in negative-magnetostrictive amorphous wires was qualitatively clarified considering their magnetic domain model and using measurements of BH hysteresis loops regarding their circular magnetization. Three kinds of amorphous wires of FeSiB, CoSiB and FeCoSiB having diameter of 120-μm and 50-μm were investigated. It was found that the Matteucci voltage was determined by the differential permeability of the BH hysteresis loops which showed the highest value in a slightly negative magnetostrictive FeCoSiB wire (λs=0.1×10-6). Variation characteristics of the Matteucci voltage for applied tension and annealing are also explained using the BH characteristics. Three kinds of Matteucci effects were expressed applying (i) an ac wire current, (ii) a perpendicular ac field and (iii) a high frequency wire current and a low frequency perpendicular ac field. These effects are the basis for the constitution of a new data tablet and new rotary encoder.View full abstractDownload PDF (331K) -
S. Ueno, K. Tazume, H. Eguchi1992 Volume 16 Issue 3 Pages 566-569
Published: June 01, 1992
Released on J-STAGE: January 11, 2013
JOURNAL OPEN ACCESSWe have observed a phenomenon that flows of gases such as carbon dioxide and oxygen are blocked by magnetic fields. A model called a “magnetic curtain” has been introduced to explain this phenomenon. It is assumed that the magnetic curtain is a wall of air which is made by magnetic fields. In this study, we simulated flows of gases in gradient magnetic fields, introducing a model based upon molecular dynamics. It is assumed that gas molecules such as nitrogen and oxygen are particles, and further assumed that those particles move in a two dimensional space. Paramagnetic oxygen is accelerated by magnetic force determined by the product of magnetic field and the gradient. We simulated trajectories of gas flow in gradient magnetic fields at various maximal magnetic forces (fmax). With nitrogen gas, gas flow is clearly disturbed at fmax=10-15 N. However, in the experiment the blocking of gas flow is observed at fmax= 10-23 N. This difference may be explained by the interaction between magnetic fields and mass behavior of particles as a group.View full abstractDownload PDF (171K) -
O. Hiwaki, S. Ueno1992 Volume 16 Issue 3 Pages 570-575
Published: June 01, 1992
Released on J-STAGE: January 11, 2013
JOURNAL OPEN ACCESSThis study focused on the properties of nerve excitation responding to pulsed electric fields induced by time-varying magnetic fields. We carried out magnetic stimulation of the human brachial plexus by localized and vectorial stimulation using a sequence of rectangular electric fields induced by trapezoidal magnetic fields. The results show that the nerve excitation is suppressed when plateau of trapezoid is shorter than a critical value. We introduced a model to explain this phenomenon. The nerve excitation elicited by magnetically induced electric fields was simulated. A computer simulation shows that the threshold for nerve excitation elicited by the trapezoidal magnetic field decreases with the increase of plateau of the trapezoidal magnetic field.View full abstractDownload PDF (283K) -
T. Sato, T. Yamada1992 Volume 16 Issue 3 Pages 576-579
Published: June 01, 1992
Released on J-STAGE: January 11, 2013
JOURNAL OPEN ACCESSThe effects of chemical thinning after annealing were examined on two kinds of amprphous Fe-base alloy ribbons with different thicknesses (25, 60 μm) to further improve their core loss. The core loss of a 60μm thick ribbon continued to decrease with thickness reduction and reached a minimum (0.04 W /kg at 50 Hz and 1.3 T) at 10μm. This value is perhaps the least ever reported. On the other hand, for a 25μm thick ribbon treated in the same manner, a minimum of the core loss was as large as 0.09 W /kg. The very low core loss of a thick ribbon results from low hysteresis loss which remains constant in a wide thickness range during thinning. The low hysteresis loss of a thick amorphous ribbon is possibly due to its high structural homogeneity.View full abstractDownload PDF (614K) -
K. Nakajima, T. Miyazaki1992 Volume 16 Issue 3 Pages 580-583
Published: June 01, 1992
Released on J-STAGE: January 11, 2013
JOURNAL OPEN ACCESSA measurement system of surface magneto-optic Kerr effect (SMOKE) has been newly developed. The sensitivity is 5×10-4 degrees and an absolute value of the rotation angle can be measured. Kerr rotation θk and ellipticity ηk of Co thin films deposited on glass substrates in an ultra high vacuum were measured in-situ. When the film thickness was thicker than 80 Å, experimental values were in good agreement with those of numerical calculation, in which n, k and magneto-optical constant Q0 of 130 Å thick Co film were used. However, θk and ηk decreased drastically for films thinner than 40 Å and were nearly zero below about 18 Å.View full abstractDownload PDF (214K) -
S. Mitani, H. Toyoda, M. Doi, M. Matsui1992 Volume 16 Issue 3 Pages 584-589
Published: June 01, 1992
Released on J-STAGE: January 11, 2013
JOURNAL OPEN ACCESSFcc-Fe/Cu(Au) artificial superlattiees were prepared on Cu(001) by an MBE method. The interatomic distance of fcc-Fe is controlled by Cu(Au) alloy layers epitaxially grown in multilayered films. Epitaxial growth and artificial periodicity of films were examined by RHEED and X-ray diffraction. Saturation magnetization of the films was measured. All fcc-Fe films show ferromagnetism having Tc above room temperature (400～580 K). Magnetic moment of an Fe atom increases up to 2.5～2.7 μB with increases in the interatomic distance.View full abstractDownload PDF (1012K) -
K. Nakanishi, O. Shimizu, S. Yoshida1992 Volume 16 Issue 3 Pages 590-593
Published: June 01, 1992
Released on J-STAGE: January 11, 2013
JOURNAL OPEN ACCESSThe effects of thickness, uniaxial anisotropy field, electrical resistivity, and element addition on frequency dependence of permeability in Fe-Zr-N films were investigated. Film thickness was up to 8μm. The purpose of our study was to clarify the main origin of high frequency loss in those thick films in order to apply them to magnetic heads. The results showed that the main origin of loss was eddy current for high anisotropy film. Although anisotropy dispersion existed, permeability for magnetic head drive frequency of lower than 30 MHz is explained by using the classical equation of eddy current loss with the effective uniaxial anisotropy field. On the other hand, the permeability for low anisotropy film disagrees with the result obtained by the classical equation. The effect of the anisotropy dispersion should be considered to explain the permeability of those low anisotropy films.View full abstractDownload PDF (215K) -
R. Aoyama, Y. Sakaki, M. Ogura, M. Kato1992 Volume 16 Issue 3 Pages 594-597
Published: June 01, 1992
Released on J-STAGE: January 11, 2013
JOURNAL OPEN ACCESSThis paper describes a study on the distribution of magnetite particles in the head of sockeye salmon. The magnetite particles are found not only in ethmoid tissues but in whole tissues in the head. Further, the magnetite particles are highly distributed near the brain. This suggests that a new magnetic sense organ may exist near the brain.View full abstractDownload PDF (481K)
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