ITE Technical Report
Online ISSN : 2424-1970
Print ISSN : 1342-6893
ISSN-L : 1342-6893
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32.55
Displaying 1-17 of 17 articles from this issue
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  • [title in Japanese]
    Article type: Cover
    Pages Cover1-
    Published: December 11, 2008
    Released on J-STAGE: September 20, 2017
    DOIhttps://doi.org/10.11485/itetr.32.55.0_Cover1
    CONFERENCE PROCEEDINGS FREE ACCESS
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  • [title in Japanese]
    Article type: Index
    Pages Toc1-
    Published: December 11, 2008
    Released on J-STAGE: September 20, 2017
    DOIhttps://doi.org/10.11485/itetr.32.55.0_Toc1
    CONFERENCE PROCEEDINGS FREE ACCESS
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  • Relationship between image distortion and bit error characteristics
    Yosuke TAKAHATA, Yuta KAJIWARA, Yuichiro SASA, Manabu YAMAMOTO
    Article type: Article
    Session ID: MMS2008-68
    Published: December 11, 2008
    Released on J-STAGE: September 20, 2017
    DOIhttps://doi.org/10.11485/itetr.32.55.0_1
    CONFERENCE PROCEEDINGS FREE ACCESS
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    In hologram multiplexed recording, the distortion of reproduced images are caused by the optical system aberration or medium shrinkage by the polymerization process. With the increase in the volume of page data, these distortions increase the bit error rate. Therefore, it is needed to study precise characteristics of the influence of image distortion in the multiplexed recording. In this paper, we studied the bit error characteristics caused by a brightness value irregularity with the shrinkage of the medium or optical system aberration.
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  • Analysis of recording characteristics of photopolymers in holographic memory
    Keita SHIMADA, Naruki YOSHIDA, Yuko SEKI, Manabu YAMAMOTO
    Article type: Article
    Session ID: MMS2008-69
    Published: December 11, 2008
    Released on J-STAGE: September 20, 2017
    DOIhttps://doi.org/10.11485/itetr.32.55.0_7
    CONFERENCE PROCEEDINGS FREE ACCESS
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    A photopolymer must satisfy certain criteria to qualify as a practical recording medium. However, the reaction processes of such photopolymers are highly complicated. In this study, we have simulated the formation of diffraction gratings in photopolymers using the diffusion model based on elementary reactions, and analyzed their diffraction characteristics in detail by the beam propagation method. Moreover, we also performed experimental interference fringe recording and evaluated the recording characteristics of photopolymer media.
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  • New HDD-market perspective
    Naoki Kodama, Yuji Nishimura, Hiroshi Nishida, Fumio Kugiya
    Article type: Article
    Session ID: MMS2008-70
    Published: December 11, 2008
    Released on J-STAGE: September 20, 2017
    DOIhttps://doi.org/10.11485/itetr.32.55.0_13
    CONFERENCE PROCEEDINGS FREE ACCESS
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    HDD has been developed as data storages for PC and Server-system. New market is growing last a few years. One is Auto-HDD market, which is used as car-storage with very strict environmental specifications such as wide range temperature. The other is an iVDR (information Versatile Disk for Removable usage) market which is a removable HDD. Removable HDDs with USB connectors have been developed and the market is strongly growing. The iVDR with data protection function for TV programs, movie contents has been developing as a balanced storage with data-security, reasonable data-capacity and price from 2007. This report surveys new HDD markets with customer requirements and developing HDD status.
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  • A Study on SOVA decoder for iterative decoding in perpendicular magnetic recording
    Yasuaki NAKAMURA, Shintaro HARUGAICHI, Yoshihiro OKAMOTO, Hisashi OSAW ...
    Article type: Article
    Session ID: MMS2008-71
    Published: December 11, 2008
    Released on J-STAGE: September 20, 2017
    DOIhttps://doi.org/10.11485/itetr.32.55.0_19
    CONFERENCE PROCEEDINGS FREE ACCESS
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    It is an issue that the iterative decoding system using the soft-output information based on a posteriori probability(APP) requires the huge memory. In this paper, the amount of required memory and the bit error rate performance are evaluated for two kinds of systems in a perpendicular magnetic recording channel model. A low density parity check(LDPC) code obtained by interleaving the overall code words and a structured random interleaved array(RIA)-LDPC code are combined with either soft output Viterbi algorithm(SOVA) decoder or APP decoder. The results show that the system adopting the RIA-LDPC code and the SOVA decoder reduces the memory by approximately 97% compared to the combined system of another LDPC code and the APP decoder, while the SNR degrades about 0.4dB.
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  • Analysis of perpendicular magnetic recording signal distribution and its separation by hyper-plane
    Seiichi MITA, Fumiya HAGA
    Article type: Article
    Session ID: MMS2008-72
    Published: December 11, 2008
    Released on J-STAGE: September 20, 2017
    DOIhttps://doi.org/10.11485/itetr.32.55.0_25
    CONFERENCE PROCEEDINGS FREE ACCESS
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    We have checked the log likelihood ratio distributions of perpendicular magnetic recording signal at a error rate of approximately 10^<-3>. We s how that t hese distributions are different among every three-bit patterns. We also generate hyper-planes to discriminate these patterns with support vector machine (SVM) using RBF Kernel. For visualization, we present these distributions in three dimensional space based on the log likelihood ratios. Erroneous signals are clearly discriminated by these hyper-planes
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  • Road map of stress assisted magnetization reversal for perpendicular MRAM
    Naoya SAITO, Shigeki NAKAGAWA
    Article type: Article
    Session ID: MMS2008-73
    Published: December 11, 2008
    Released on J-STAGE: September 20, 2017
    DOIhttps://doi.org/10.11485/itetr.32.55.0_31
    CONFERENCE PROCEEDINGS FREE ACCESS
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    MRAM has been regarded as a next generation memory. However, high power consumption arising from writing process is one of the demerits for practical realization. So we have proposed a stress assisted magnetization reversal (SAMR) method for perpendicular MRAM. In our previous study, perpendicular magnetization of DyFeCo thin films, that have 1400 Oe of original coercivity, could be reversed at 200 Oe field by applying 330 MPa stress. In this study, Terfenol-D was focused as giant magnetostrictive material to attain magnetization reversal at lower stress. Additionally, a guideline to attain magnetization reversal at lower stress and lower field was discussed based on measurement results.
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  • Excellent scalability of Magnetic Random Access Memory using spin transfer switching and perpendicular magnetic anisotropy
    Masahiko Nakayama, Tadashi Kai, Hisanori Aikawa, Junichi Ozeki, Katsuy ...
    Article type: Article
    Session ID: MMS2008-74
    Published: December 11, 2008
    Released on J-STAGE: September 20, 2017
    DOIhttps://doi.org/10.11485/itetr.32.55.0_37
    CONFERENCE PROCEEDINGS FREE ACCESS
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    Low switching current and Large thermal stability factor is important for achieving a high-density MRAM using spin transfer switching. In this paper, the spin transfer switching current and the thermal stability factor as functions of a diameter of magnetic tunnel junction (MTJ) with the perpendicular magnetic anisotropy is investigated by micromagnetic simulations based on an LLG equation. With the diameter of MTJ decreasing, the spin transfer switching efficiency I_c/ΔEα also decreasing. These calculated results clearly show that the MRAM using the spin transfer switching and the perpendicular magnetic anisotropy have excellent scalability for the high density RAM.
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  • USE OF SPECULAR OPTICAL SYSTEM TO MEASURE HDD SLIDER FLYING HEIGHT TO A HIGH LEVEL OF ACCURACY
    Akiyoshi Uchida, Goroh Kawasaki, Kiyoto Matsui, Yoshihide Fujita, Masa ...
    Article type: Article
    Session ID: MMS2008-75
    Published: December 11, 2008
    Released on J-STAGE: September 20, 2017
    DOIhttps://doi.org/10.11485/itetr.32.55.0_43
    CONFERENCE PROCEEDINGS FREE ACCESS
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    Finding a method of accurately measuring ultra-low flying heights (FH) of an HDD slider is becoming more and more important. We have developed a way of using a specular optical system to measure the FH to a high level of accuracy. While the basic method is to measure the height of a slider flying over a bare glass disk, this method can also be used to measure one flying over a glass disk with a overcoat (OC) and a lubricant agent (Lube) and thus to observe the touch down (TD) or the take off (TO) behavior. We theoretically investigated the effect of the OC and the Lube layer on the accuracy of the measurement and a method to compensate for their effect. With this compensation, we could measure the FH using a glass disk with OC and Lube.
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  • A Study of Magnetostatic Interaction and Write Margin of Staggered Patterned Media
    Naomichi DEGAWA, Simon Greaves, Hiroaki MURAOKA, Yasushi KANAI
    Article type: Article
    Session ID: MMS2008-76
    Published: December 11, 2008
    Released on J-STAGE: September 20, 2017
    DOIhttps://doi.org/10.11485/itetr.32.55.0_49
    CONFERENCE PROCEEDINGS FREE ACCESS
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    The assignment of bit-patterned media (BPM) with high recording density is to reduce interference of magnetostatic interaction and adjacent track eraser (ATE). Therefore, it is effective to have the large space between adjacent dots. In this report, write margin and magnetostatic interaction of staggered bit-patterned media (BPM) with array of half bit shifted dot in down track direction were investigated and compared with square bit patterned media with regular dot array. There is no distinguished difference in both magnetostatic interactions, however, distributions of magnetostatic interaction depend on dot arrays. Staggered BPM could reduce ATE and get the larger effective margin than square BPM.
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  • Effect of Head-Medium Magneto-static Interaction on Recorded Magnetization Distribution
    Kinya FUDANO, Yoshihisa NAKAMURA
    Article type: Article
    Session ID: MMS2008-77
    Published: December 11, 2008
    Released on J-STAGE: September 20, 2017
    DOIhttps://doi.org/10.11485/itetr.32.55.0_55
    CONFERENCE PROCEEDINGS FREE ACCESS
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    In order to achieve ultra high density recording in perpendicular magnetic recording systems, the simulation is much useful tool for understanding the mechanisms of recording processes, and these results are fed back to the designs of heads and recording media materials and configurations. To simulate the recording process accurately, the authors have been combined a finite element method (FEM) with a magnetization reversal model for magnetic fine particles and introduced the self-consistent magnetization calculation, in which the magneto-static interaction between a head and a medium is taken into account. By using this simulator, called "SMART" , the several recording processes have been analyzed precisely and discussed the results from the viewpoint of the effect of the head-medium magneto-static interaction on the head field distributions and then the magnetization distributions on recording media after writing.
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  • FEM static and micromagnetic dynamic recording field analysis of a single-pole-type head
    Kazunori HIRASAWA, Kazuya KOYAMA, Yoshihiro JINBO, Yasushi KANAI, Kazu ...
    Article type: Article
    Session ID: MMS2008-78
    Published: December 11, 2008
    Released on J-STAGE: September 20, 2017
    DOIhttps://doi.org/10.11485/itetr.32.55.0_61
    CONFERENCE PROCEEDINGS FREE ACCESS
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    FEM static field analysis were performed to optimize the single-pole-type (SPT) head for 2 terabit/in^2 with regard to obtaining a high field gradient. Using the optimized head field, micromagnetic media simulation was done for bit-patterned media. A head field response was obtained for a high frequency driving current using the Landau-Lifshitz-Gilbert micromagnetic recording field analysis. In micromagnetic LLG head simulation, we used parallel program with Open Multi-Processing (Open MP) and multi-core symmetric multi processing (SMP) system.
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  • LLG Simulation for Microwave Assisted Magnetic Recording : Reduction of The Switching field by Magnetic Resonance
    Masukazu IGARASHI, Yoshio SUZUKI, Harukazu Miyamoto, Yoji MARUYAMA, Yo ...
    Article type: Article
    Session ID: MMS2008-79
    Published: December 11, 2008
    Released on J-STAGE: September 20, 2017
    DOIhttps://doi.org/10.11485/itetr.32.55.0_67
    CONFERENCE PROCEEDINGS FREE ACCESS
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    The characteristics of magnetization switching assisted by microwave for an isol ation particle was investigated by the LLG simulation, fol lowing results we re obtained. 1) The anticlockwise AC field that is s ame direct ion of the rot ation as the pre cession of the magnetization contributes to the switch. In clockwise AC field, there is an influence of re-switch. 2) Linear polarization AC field includes the anticlockwise and clockwise AC fields, and there is worry that a saturation recording is not obtained. 3) AC field that is larger than about 10 percent of the a nisotropic field is nec essary for the ach ievement of a large effect of m icrowave as sistance. 4) The effect of assistance increases and the switching field distribution decreases in an exchange coupled media.
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  • [title in Japanese]
    Article type: Appendix
    Pages App1-
    Published: December 11, 2008
    Released on J-STAGE: September 20, 2017
    DOIhttps://doi.org/10.11485/itetr.32.55.0_App1
    CONFERENCE PROCEEDINGS FREE ACCESS
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  • [title in Japanese]
    Article type: Appendix
    Pages App2-
    Published: December 11, 2008
    Released on J-STAGE: September 20, 2017
    DOIhttps://doi.org/10.11485/itetr.32.55.0_App2
    CONFERENCE PROCEEDINGS FREE ACCESS
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  • [title in Japanese]
    Article type: Appendix
    Pages App3-
    Published: December 11, 2008
    Released on J-STAGE: September 20, 2017
    DOIhttps://doi.org/10.11485/itetr.32.55.0_App3
    CONFERENCE PROCEEDINGS FREE ACCESS
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