Research Institute for Electrical and Magnetic Materials

Sendai-shi, Japan

Research Institute for Electrical and Magnetic Materials

Sendai-shi, Japan
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Hashi S.,Tohoku University | Ishiyama K.,Tohoku University | Yabukami S.,Tohoku Gakuin University | Kanetaka H.,Tohoku University | Arai K.I.,Research Institute for Electrical and Magnetic Materials
Journal of Applied Physics | Year: 2010

Integration of the exciting coil and the pick-up coil array for the wireless magnetic motion sensing system has been investigated to clear the limitation of the system arrangement. From the comparison of the integrated-type and the sandwich-type, which was proposed by our previous study, regardless of the lower signal-to-noise ratio of the integrated-type than that of the sandwich-type a repeatable detection accuracy of around 1 mm is obtained at the distance of 120 mm from the pick-up coil array (sandwich-type: up to 140 mm). A different tendency of the detection errors in detection was also observed. In spite of different tendency, the cause of the errors has been clarified. The impedance change of the exciting coil due to a resonance of the LC marker perturbs strength of the magnetic field which is used for marker excitation. However, the errors are able to compensate to the actual positions and orientations of the marker by using compensatory method which was already established. © 2010 American Institute of Physics.


Hashi S.,Tohoku University | Yabukami S.,Tohoku Gakuin University | Kanetaka H.,Tohoku University | Ishiyama K.,Tohoku University | Arai K.I.,Research Institute for Electrical and Magnetic Materials
IEEE Transactions on Magnetics | Year: 2011

With the aim of improving the detection accuracy of a wireless magnetic position-sensing system using an LC resonant magnetic marker, a pickup coil with an optimal size (10 mm in diameter × 1 mm thick), as calculated by a previous simulation study, was used and tested in this paper. Our study confirmed that positional errors were reduced to a submillimeter order in the area within y=120 mm from the pickup coil array. On the contrary, in the area outside y=130 mm from the pickup coil array, the errors increased by about 0.5-2 mm compared to the results for the previous pickup coil size (25 mm in diameter × 2 mm thick). Regardless of the size of the pickup coil, however, compensation can be made for these positional deviations, including the influence of the mutual inductance between the LC marker and the exciting coil. After application of the compensation process, the detection results were corrected approximately to the actual positions of the LC marker. © 2011 IEEE.


Hashi S.,Tohoku University | Yabukami S.,Tohoku Gakuin University | Ishiyama K.,Tohoku University | Arai K.I.,Research Institute for Electrical and Magnetic Materials
Sensor Letters | Year: 2013

We have investigated downsizing of the LC resonant magnetic marker of the wireless magnetic position detection system for medical applications. Two shapes of ferrite cores, which are a needletype and a plate-type, were examined for use in the core of the LC marker. The system was capable of wirelessly detecting the position of downsized small LC markers (except for the ferrite core of 1 mm in diameter and 5 mm in length) with an accuracy on the order of less than 90 mm from the pick-up coil array. Comparison of the prepared cores and the large ferrite core (of 3 mm in diameter and 10 mm in length) as the LC marker revealed that the S/N ratio of the LC marker signal was decreased due to core volume reduction. However, the effect of the demagnetizing factors related to core shape was greater than that of the volume reduction that reduced the S/N ratio and the position accuracy of the system. Copyright © 2013 American Scientific Publishers All rights reserved.


Ohnuma S.,Research Institute for Electrical and Magnetic Materials | Ohnuma S.,Tohoku University | Masumoto H.,Tohoku University
Journal of Magnetics | Year: 2011

Metal-insulator type, nano-granular soft magnetic films have been reviewed from the viewpoint of high frequency magnetic materials. The formation of nano-granular structure is related to the magnitude of heat of formation of intergranule materials. Variation of the ratio of granule phase to intergranule phase in the film is found to produce various characteristics in the magnetic properties of the film. The HRTEM observation reveals that neighboring granules in the film with above 60 at.% Co, contact at considerable points and the films show soft magnetic properties which are explainable in terms of the random anisotropy model for nanocrystalline materials. Addition of Ni group elements in Co-O based films enhances their anisotropy field up to 400 Oe and they exhibit excellent frequency response of permeability. Also, large electromagnetic noise suppression effect is demonstrated as one of their potential applications. © 2011 Journal of Magnetics.


Abe S.,Research Institute for Electrical and Magnetic Materials | Ping D.H.,Research Institute for Electrical and Magnetic Materials | Usui H.,Research Institute for Electrical and Magnetic Materials | Ohnuma M.,Research Institute for Electrical and Magnetic Materials | Ohnuma S.,Research Institute for Electrical and Magnetic Materials
Thin Solid Films | Year: 2010

This study investigated the preparation and particle size control of nanocrystalline magnetite (Fe3O4) containing a small amount of Ge. Thin films were prepared by radio-frequency sputtering with a composite target of Ge chips set on a Fe3O4 compound target in a mixed atmosphere of Ar and O2. X-ray diffraction revealed that the diffraction peak of magnetite gradually broadened as the oxygen ratio increased, with the mean grain size ranging from 26 to 2 nm. Transmission electron microscopy also revealed that the magnetite structurally changed from polycrystalline single phase to isolated granular nanocrystals. Magnetization at 8 × 105 A/m was monotonically reduced from 0.32 to 0.04 T, and coercivity was monotonically reduced from 4.2 × 104 to 2.1 × 103 A/m with increasing the oxygen ratio from 0 to 0.4%. © 2009 Published by Elsevier B.V. All rights reserved.


Kobayashi N.,Research Institute for Electrical and Magnetic Materials | Masumoto T.,Research Institute for Electrical and Magnetic Materials
IEEJ Transactions on Fundamentals and Materials | Year: 2012

The structure and tunnel magneto-resistance of (Fe-Ni or Fe-Co)-(Mg-F) nano-granular thin films were investigated. The films were prepared by a tandem deposition method, using Fe-Ni or Fe-Co alloy and MgF 2 insulator targets. A granular structure was found to be consisted of Fe-Ni or Fe-Co based nano-granules surrounded by thin intergranules of Mg based fluoride which were crystallized with a MgF 2 structure. These films show tunnel-type magnetoresistance which is caused by the film structure. The GIGS. (Granular-in-Gap-Sensor) consisting of the (Fe-Co)-(Mg-F) nano-granular thin film filled into a narrow gap of soft magnetic a-CoFeSiB thin film was prepared. GIGS. has large electrical resistance (10 kΩ -10 MΩ) because of high electrical resistivity of metal-nonmetal nano-granular film. The large electric resistivity causes the reduction of the electricity consumption. © 2012 The Institute of Electrical Engineers of Japan.


Abe S.,Research Institute for Electrical and Magnetic Materials
Nanoscale Research Letters | Year: 2011

This study investigates the preparation of PbSe-ZnSe composite thin films by simultaneous hot-wall deposition (HWD) from multiple resources. The XRD result reveals that the solubility limit of Pb in ZnSe is quite narrow, less than 1 mol%, with obvious phase-separation in the composite thin films. A nanoscale elemental mapping of the film containing 5 mol% PbSe indicates that isolated PbSe nanocrystals are dispersed in the ZnSe matrix. The optical absorption edge of the composite thin films shifts toward the low-photon-energy region as the PbSe content increases. The use of a phase-separating PbSe-ZnSe system and HWD techniques enables simple production of the composite package. © 2011 Abe.


Abe S.,Research Institute for Electrical and Magnetic Materials | Ping D.H.,Japan National Institute of Materials Science | Ohnuma M.,Japan National Institute of Materials Science | Ohnuma S.,Research Institute for Electrical and Magnetic Materials
Japanese Journal of Applied Physics | Year: 2011

In this study, we investigate the transformation mechanism from a phase mixture of magnetite (Fe3O4) and hematite (α-Fe 2O3) to a single-phase magnetite through the addition of a specific metal element. The thin films were prepared by rf sputtering with a composite target of metal chips set on a ceramic magnetite (or hematite) target in Ar atmosphere. It is revealed that the addition of Ge to the polycrystalline hematite film obviously produces single-phase magnetite, indicating that the hematite is fully transformed to magnetite through an addition of Ge. Such transformation is also seen with slight additions of Mo, W, Cr, and Mg, whereas the addition of Sn does not affect the phase mixture of magnetite and hematite. According to the free energy of the reaction, elements of Ge, Mo, W, Cr, and Mg are capable of reducing hematite, whereas hematite remains unreactive with addition of Sn. This is in good agreement with the experiment results. This unique technique additionally provides the maximum magnetization of 3.9kG at 8 × 105 A·m-1 (10kOe) at a Mo concentration of 1.3 at. %. © 2011 The Japan Society of Applied Physics.


Patent
Omron Corporation and Research Institute For Electrical And Magnetic Materials | Date: 2011-07-13

To improve a linearity of a magnetic detection element 7a having a magnetoresistance effect portion lOa composed of a magnetoresistance effect material and a pair of yoke portions 11a, 11b which is composed of a soft magnetic material and respectively arranged so as to be electrically connected to both sides of the magnetoresistance effect portion 10a, and which guides magnetic flux into the magnetoresistance effect portion 10a, a bypass portion 13a which is composed of a soft magnetic material and saturated with magnetic flux at lower magnetic field intensity than the yoke portions 11a, 11b, and which guides a part of the magnetic flux generated in the yoke portions 11a, 11b so as to divert the magnetic flux from the magnetoresistance effect portion 10a is provided.


PubMed | Research Institute for Electrical and Magnetic Materials
Type: Journal Article | Journal: Nanoscale research letters | Year: 2011

This study investigates the preparation of PbSe-ZnSe composite thin films by simultaneous hot-wall deposition (HWD) from multiple resources. The XRD result reveals that the solubility limit of Pb in ZnSe is quite narrow, less than 1 mol%, with obvious phase-separation in the composite thin films. A nanoscale elemental mapping of the film containing 5 mol% PbSe indicates that isolated PbSe nanocrystals are dispersed in the ZnSe matrix. The optical absorption edge of the composite thin films shifts toward the low-photon-energy region as the PbSe content increases. The use of a phase-separating PbSe-ZnSe system and HWD techniques enables simple production of the composite package.

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