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Volume 29, Issue 6
Displaying 1-7 of 7 articles from this issue
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Contributed Papers
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K. Matsuno, K. Mizuno, S. Nakagawa2005 Volume 29 Issue 6 Pages 649-652
Published: 2005
Released on J-STAGE: September 16, 2005
JOURNAL OPEN ACCESSThin films of hexagonal magneto-plumbite-type strontium ferrite with La3+ and Co2+ thin films (LaCo-SrM) substituted for Fe3+ and Sr2+ as magnetic layer with a Pt underlayer were prepared by using a facing targets sputtering system and a flash-annealing process. After the films had been deposited at a low temperature of 250°C, which was not sufficient for crystallization, the specimens were flash-annealed at a high temperature of 900°C for a few minutes. A 22-nm-thick LaCo-SrM film revealed a coercivity of 5.2 kOe, a squareness of 0.85, and a particle size of 20 nm, respectively. To further improve the magnetic properties, LaCo-SrM/Pt multilayered thin films composed of three periods were prepared. The coercivity and squareness of a 78-nm-thick (total thickness of magnetic layers) LaCo-SrM multilayered film were as high as 5.5 kOe and 0.97, respectively. The particle size was also reduced to 18 nm. Stacking the LaCo-SrM in a multilayered structure was found to be effective for improving the magnetic properties necessary for high-density recording media.View full abstractDownload PDF (102K) -
M. Tsunoda, Y. Watanabe, K. Imakita, S. Yoshimura, M. Takahashi2005 Volume 29 Issue 6 Pages 653-657
Published: 2005
Released on J-STAGE: September 16, 2005
JOURNAL OPEN ACCESSEffect of in-situ ion bombardment to Al-N barrier in magnetic tunnel junctions (MTJ) on their tunnel magnetoresistance (TMR) was investigated in correlation with the local conducting properties of Al-N barrier. Slight ion bombardment increased the barrier height of Al-N from 1.2eV to 1.8∼1.9eV, and resulted in the enhancement of TMR ratio from 34% to 37% in as-made MTJ. On the other hand, strong ion bombardment, longer bombardment duration than 10s, produced high conductive channels (pinholes) in the Al-N barrier, and deteriorated the TMR ratio down to 20% and more. Simple calculation for TMR ratio and resistance-area product of MTJs with using the pinhole density and the local conducting properties, determined from conducting-AFM measurement, well explained the experimental features.View full abstractDownload PDF (433K) -
T. Kamino, S. Saito, K. Miyokawa, M. Endo, T. Saito, T. Katayama2005 Volume 29 Issue 6 Pages 658-662
Published: 2005
Released on J-STAGE: September 16, 2005
JOURNAL OPEN ACCESSNi and Cu thin films of about 100 and 50 nm were deposited on MgO(001), (110), (111), and diamond(001) substrates by using a molecular beam epitaxy (MBE) method. Their growth mechanisms were investigated by in-situ RHEED. We found that Ni films can be grown easily on a diamond(001) substrate where the lattice mismatch between Ni and diamond is very small (1.42%). We found that, despite a large lattice mismatch of 19.5% (16.5%) between Ni (Cu) and MgO, Ni and Cu films can be grown epitaxially on MgO(001), (110), and (111) substrates. Moreover we measured magneto-optical (MO) Kerr ellipticity spectra on the epitaxial Ni films on MgO and diamond substrates. As a result, no difference of MO Kerr spectra were observed on Ni(001), (110), and (111). The epitaxial Ni films with Cu buffer layers show relatively small coercive force (Hc) compared with that of epitaxial Ni films without Cu buffer layers.View full abstractDownload PDF (1151K) -
Development of an Enhanced-Phase-Detection-Type Magnetic Field Sensor using a High-Frequency-CarrierT. Ozawa, C. Yokota, N. Horikoshi, S. Yabukami, K. Ishiyama, K. I. Ara ...2005 Volume 29 Issue 6 Pages 663-666
Published: 2005
Released on J-STAGE: September 16, 2005
JOURNAL OPEN ACCESSThe impedance of a magnetic thin film changes when a magnetic field is applied. The high-frequency-carrier magnetic field sensor, also called a GMI sensor, employs this phenomenon as its principle. We directed our attention to the change in the phase characteristic, and measured the magnetic field by measuring the phase of the high-frequency-carrier magnetic field sensor as a phase difference. Although the high-frequency-carrier magnetic field sensor is optimized for impedance detection, it is not appropriate for measuring the magnetic field by detecting the phase difference. To improve its resolution and sensitivity in this respect, we developed an enhanced-phase-difference-detection-type magnetic field sensor. As a result, we obtained a best rate of change of 63.5 degree/Oe and a resolution of 2.6 × 10-7 Oe/Hz1/2.View full abstractDownload PDF (691K) -
H. Nakayama, T. Yamamoto, Y. Mizoguchi, T. Sato, K. Yamasawa, Y. Miura ...2005 Volume 29 Issue 6 Pages 667-674
Published: 2005
Released on J-STAGE: September 16, 2005
JOURNAL OPEN ACCESSSuppression of the insertion loss of a CoFeB/polyimide hybrid thin-film coplanar line for impedance matching in a mobile phone power amplifier module was investigated. To suppress the insertion loss of the CoFeB/polyimide hybrid coplanar line, various techniques were investigated on the basis of device simulations and fabrication. As a result, it was found that the introduction of a thick copper signal line, a multilayer magnetic film structure and optimum width of the magnetic film were effective for lowering insertion loss. Insertion loss per quarter wavelength of the fabricated devices was below 0.5 dB in the frequency range from 1 to 1.5 GHz.View full abstractDownload PDF (1162K) -
T. Nakai, H. Abe, K. I. Arai2005 Volume 29 Issue 6 Pages 675-679
Published: 2005
Released on J-STAGE: September 16, 2005
JOURNAL OPEN ACCESSVariation of non-linear impedance as a function of circumferential temperature is reported. Non-linear impedance occurs in rectangular strips of thin-film soft magnetic material with a width of tens of microns and with inclined stripe domains. Sensors with different dimensions were studied with circumferential temperatures ranging from −20°C to 70°C. It was found that the change in the non-linear impedance profile had the same tendency, irrespective of the impedance profile. As the circumferential temperature increases the width of magnetic field between the non-linear impedances, these happen in case of increasing or decreasing the magnetic field, narrows. A method of compensating for the temperature drift of the magnetic field in which non-linear impedance appears is proposed. It is shown that this method compensates well for the temperature drift within the range of measurement error.View full abstractDownload PDF (396K) -
K. Tajima, M. Hattori, T. Miyaji, T. Sato, Y. Sakamoto2005 Volume 29 Issue 6 Pages 680-685
Published: 2005
Released on J-STAGE: September 16, 2005
JOURNAL OPEN ACCESSSince a laminated core parametric induction motor has a planar structure, there is a possibility of using mass production to reduce costs. In past work, we calculated the behavior characteristics of an orthogonal-core-type parametric induction motor in a locked rotor, using the reluctance network analytical model, and the analytical results showed good agreement with the experimental ones. In this paper, we examine the validity of applying the reluctance network method to the analysis of a laminated-core parametric induction motor while the rotor is driving.View full abstractDownload PDF (406K)
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