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Volume 23, Issue 4_1
Displaying 1-6 of 6 articles from this issue
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Contributed Paper
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M. Ikeda, K. Uemura, I. Sasaki, K. Mohri1999 Volume 23 Issue 4_1 Pages 920-924
Published: 1999
Released on J-STAGE: March 20, 2007
JOURNAL OPEN ACCESSThe sputtering technique was used to prepare Ni-Fe magnetostrictive films on Ti-alloy or SUS304 stainless-steel shafts for construction of torque sensors. The factors affecting the thermal drift of the torque sensors are studied as functions of the composition and the thickness of the Ni-Fe films, the thermal expansion coefficients of the Ni-Fe films and the shaft materials, and the thermal expansion coefficient of the pick-up copper coils. The optimal value of the thickness for the determined pattern width for each composition of the Ni-Fe films was found to result in minimum thermal drift of the torque sensor.View full abstractDownload PDF (321K) -
L. V. Panina, D. P. Makhnovskiy, K. Mohri1999 Volume 23 Issue 4_1 Pages 925-930
Published: 1999
Released on J-STAGE: March 20, 2007
JOURNAL OPEN ACCESSThe magneto-impedance (MI) behavior has been analyzed in multilayers having an inner conductor lead and two identical magnetic layers with a uniaxial anisotropy which is crossed in the upper film with respect to that in the lower one. Emphasis is placed on the evolution of MI characteristics under the effect of a dc biasing current, which is of interest for developing auto-biased magnetic sensors. Various types of MI can be realized in this case. Among them, asymmetrical anhysteretic MI has special importance for linear magnetic sensing. For analysis, an approximation of a weak skin effect, as well as an exact solution of Maxwell‘s equations, is used, demonstrating that for a CoSiB/Cu/CoSiB film of 1-μm thickness the skin effect can be neglected for frequencies up to the GHz band. The insertion of a conductor lead, by decreasing the resistance of the system, makes the skin effect unimportant for obtaining large impedance changes : MI of 100-250% takes place at frequencies of 10-50 MHz.View full abstractDownload PDF (469K) -
T. Suda, S. Ueno1999 Volume 23 Issue 4_1 Pages 931-934
Published: 1999
Released on J-STAGE: March 20, 2007
JOURNAL OPEN ACCESSTo clarify the effects of the magnetic and electric orientations of human red blood cells (RBCs) on blood rheology, the behaviors and sedimentation rates of RBCs in an 8-T magnetic field and 1-5 kV/m ac electric fields (1-200 kHz, sine wave) were investigated. When a mutually perpendicular horizontal 8-T magnetic field and larger than 2 kV/m ac electric field (higher than 100 kHz) were applied to RBCs suspended in a phosphate buffer solution, it was observed that all RBCs were oriented in the same direction so that their disk planes were parallel to both the electric and the magnetic fields. The sedimentation rate of RBCs was obtained by measuring their falling velocities, using recorded microscopic images. When the concentration of RBCs (hematocrit value) was 0.1-1%, the sedimentation rate was decreased by applying a mutually perpendicular horizontal 8-T magnetic field and 4 kV/m ac electric field. The change in the sedimentation rate reached 23% when the concentration of RBCs was 0.5%.View full abstractDownload PDF (418K) -
T. Kanbe, I. Tamai, Y. Takahashi, K. Tanahashi, A. Ishikawa, Y. Matsud ...1999 Volume 23 Issue 4_1 Pages 935-938
Published: 1999
Released on J-STAGE: March 20, 2007
JOURNAL OPEN ACCESSWe developed a non-magnetic (CoCrx)Zry [x = 30-40 at%, y = 7-14 at%] seed layer for CoCrPt glass media and investigated the dependence of the media noise and the microstructure on the Zr content of the seed layer. Media with a (CoCr30)Zr10 seed layer showed lower media noise owing to reduced grain size in the magnetic layer than the media with a Ta/Zr seed layer (refs. 1 and 2), which in turn had lower media noise than the media with a Cr seed layer. The Zr content of the seed layer should be less than 10 at%, because the grain size in the magnetic layer increased drastically (∼80%) when the Zr content was increased from 10 to 14 at%. The (CoCr30)Zr10 seed layer had a nanocrystalline structure, while the (CoCr30)Zr14 layer was almost amorphous. A seed layer with a nanocrystalline structure seems to be effective for reducing the grain size in the magnetic layer.View full abstractDownload PDF (361K) -
T. Kohda, Y. Otani, S. G. Kim, K. Fukamichi, O. Kitakami, Y. Shimada1999 Volume 23 Issue 4_1 Pages 939-942
Published: 1999
Released on J-STAGE: March 20, 2007
JOURNAL OPEN ACCESSEpitaxial arrays of (10·0) Co circular dots with diameters of 0.3 μm and 2.0 μm were prepared by electron-beam lithography and Ar ion etching. Magnetization reversal processes influenced by well-defined magnetocrystalline anisotropy were examined with a magnetic force microscope (MFM) and a vector SQUID magnetometer. The coercive force of both dot arrays is lower than that of an epitaxial Co film. From MFM and vector magnetization measurements, a magnetic vortex-like structure was found to be formed during the demagnetization process for a 0.3 μm circular dot array. In contrast, a symmetrical domain structure was formed during the demagnetization process for a 2.0 μm dot array.View full abstractDownload PDF (409K) -
W. Suenaga, Y. Shimamura1999 Volume 23 Issue 4_1 Pages 943-948
Published: 1999
Released on J-STAGE: March 20, 2007
JOURNAL OPEN ACCESSDatacarrier technology is used in a remote readable ID tag system composed of tags, an encoder, and a writer. In previous papers, the authors presented the results of a study of the characteristics of a tag composed of an amorphous strip and a magnetic tape from the viewpoint of its practical application. Several problems have remained unsolved, particularly concerning the reader, such as how to reduce its power consumption and size, how to eliminate external noise, and how to improve the reading distance. In this paper, we propose a portable reader with a superheterodyne detection system. The antenna of the reader is controlled in such a way as to resonate at the resonant frequencies of a tag. By studying the relationship between the reading distance and the characteristics of the tag, we proved experimentally that the reading distance is proportional to the square root of the product of the coupling factor K and the Q-value. The information on a tag could be read at a distance of 0.7 m by the reader with an antenna 0.3 m in diameter.View full abstractDownload PDF (418K)
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