ITE Technical Report
Online ISSN : 2424-1970
Print ISSN : 1342-6893
ISSN-L : 1342-6893
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32.23
Displaying 1-14 of 14 articles from this issue
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  • [title in Japanese]
    Article type: Cover
    Pages Cover1-
    Published: June 12, 2008
    Released on J-STAGE: September 20, 2017
    DOIhttps://doi.org/10.11485/itetr.32.23.0_Cover1
    CONFERENCE PROCEEDINGS FREE ACCESS
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  • [title in Japanese]
    Article type: Index
    Pages Toc1-
    Published: June 12, 2008
    Released on J-STAGE: September 20, 2017
    DOIhttps://doi.org/10.11485/itetr.32.23.0_Toc1
    CONFERENCE PROCEEDINGS FREE ACCESS
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  • Simulation Study of Bit Patterned Media at Areal Density of 5 Tbit/in^2
    Naoki HONDA, Kiyoshi YAMAKAWA, Kazuhiro OUCHI
    Article type: Article
    Session ID: MMS2008-30
    Published: June 12, 2008
    Released on J-STAGE: September 20, 2017
    DOIhttps://doi.org/10.11485/itetr.32.23.0_1
    CONFERENCE PROCEEDINGS FREE ACCESS
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    Recording simulation at 5 Tbit/in^2 was studied by simulation for bit patterned media with inclined anisotropy which could decrease the effect of magnetostatic interaction between dots. Recording with a shielded planar head revealed relatively large write shift margin of around 5 nm in down- and cross-track directions even at an areal density of 5 Tbit/in^2. The simulation indicated that present system can have tolerance of around 4 % in H_k dispersion and 4 degrees in orientation dispersion. Proposed system would be one of promising techniques for realizing areal density of 5 Tbit/in^2.
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  • Study of write margins for 2 Tbit/in^2 bit patterned media
    Naomichi DEGAWA, Simon Greaves, Hiroaki MURAOKA, Yasushi KANAI
    Article type: Article
    Session ID: MMS2008-31
    Published: June 12, 2008
    Released on J-STAGE: September 20, 2017
    DOIhttps://doi.org/10.11485/itetr.32.23.0_7
    CONFERENCE PROCEEDINGS FREE ACCESS
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    The characteristics of bit patterned media with an areal density of 2 Tbit/in^2 were investigated using micromagnetic simulations. The influence of dot size and position dispersions on the signal to noise ratio (SNR) was clarified. The head medium synchronization tolerance (Write margin) for error-free writing was calculated, and the feasibility of achieving 2 Tbit/in^2 recording with bit patterned media was demonstrated. In a medium with size/position dispersions, SNR decreased. Errors occurred when the magnetization of the target and next dots were opposed. Write margin depends on the head field gradient and a higher head field gradient improves recording performance. The write margin for a medium with M_s of 860 emu/cm^3 and dispersions (σK_u=10%, σθ=3°, σP=1nm, σS=15%) was a maximum of 8 nm when using a head field gradient of 511 Oe/nm.
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  • Examination of prototype shielded planar write head
    Kazuyuki ISE, Takanori KIYA, Masaru UCHIDA, Kiyoshi YAMAKAWA
    Article type: Article
    Session ID: MMS2008-32
    Published: June 12, 2008
    Released on J-STAGE: September 20, 2017
    DOIhttps://doi.org/10.11485/itetr.32.23.0_13
    CONFERENCE PROCEEDINGS FREE ACCESS
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    The shielded planar write head which combined the tapered main pole for strong write head field and wraparound shield for steep head field distribution have been fabricated. For fabrication the new head, anisotropy etching pits of Si were used as a template and magnetic yoke material was embedded in the template for formation of tapered man-pole tip. As a result, this new head was fabricated using novel technique that is different from that for present recording heads. First recording test of the head was done.
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  • Magnetoresistance of FeCo Nanocontacts With Current-Perpendicular-to-Plane Spin-Valve Structure
    Masayuki Takagishi, Hiromi Niu Fuke, Susumu Hashimoto, Hitoshi Iwasaki
    Article type: Article
    Session ID: MMS2008-33
    Published: June 12, 2008
    Released on J-STAGE: September 20, 2017
    DOIhttps://doi.org/10.11485/itetr.32.23.0_19
    CONFERENCE PROCEEDINGS FREE ACCESS
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    We have achieved a magnetoresistance (MR) ratio of 7%-10% at a resistance area product (RA) of 0.5-1.5Ωμm^2 by ferromagnetic FeCo nanocontacts in Al nano-oxide-layer (NOL) with current-perpendicular-to-plane spin-valve (CPP-SV) structure. Conductive atomic-force-microscopy shows clear current-path regions of a few nanometers in size surrounded by the Al.NOL. The MR dependence on resistance area product (RA) is well explained by the current-confined-path model assuming that the spin-dependent scattering has an FeCo nanocontact origin, different from tunnel magnetoresistance (TMR). Resistance increases with increasing bias voltage, indicating joule heating by high-current density in nanocontacts, in contrast to TMR. The MR origin is mainly interpreted as spin-dependent scattering due to domain wall formed at ferromagnetic nanocontact.
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  • Effect of Current Confined Path on Spin Torque Noise in CPP-GMR Heads with a Current Screen Layer
    Masato SHIIMOTO, Hiroyuki KATADA, Kazuhiro NAKAMOTO, Hiroyuki HOSHIYA, ...
    Article type: Article
    Session ID: MMS2008-34
    Published: June 12, 2008
    Released on J-STAGE: September 20, 2017
    DOIhttps://doi.org/10.11485/itetr.32.23.0_25
    CONFERENCE PROCEEDINGS FREE ACCESS
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    We investigated the effect of current-confined-path on spin-torque noise in current-perpendicular-to-the-plane giant-magnetoresistive (CPP-GMR) heads with a current screen layer (a nano oxide layer having current-confined-paths). We found that the current screen structure is effective in suppressing the spin-torque noise. Because, magnetization fluctuation in conductive areas can be reduced by magnetic coupling with magnetization in nonconductive areas. To reduce spin-torque noise, it is effective to reduce the area of each metallic nano-hole while keeping the total conductive area constant, since the magnetic coupling between the magnetization in conductive areas and that in nonconductive areas is enhanced.
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  • Influence of track-edge magnetization on track density
    Kenji MIURA, Toshiyuki OGAWA, Hiroaki MURAOKA, Hajime AOI, Yoshihisa N ...
    Article type: Article
    Session ID: MMS2008-35
    Published: June 12, 2008
    Released on J-STAGE: September 20, 2017
    DOIhttps://doi.org/10.11485/itetr.32.23.0_31
    CONFERENCE PROCEEDINGS FREE ACCESS
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    In order to realize higher track density, improving recording resolution and noise at track-edge is one of crucial issues. It has been considered that the erase band (EB) which appears at track-edge can suppress the cross-talk noise from the adjacent track. On the other hand, the erase band consists of a randomly-magnetized area that may emanate track-edge noise. In this study, we estimated the accurate erase band width by a newly proposed technique and derived analytical formula of the 747 curve with large erase band noise. As a result, we found that the peak of track-edge noise corresponds to the EB position and the EB was enough of a noise source at track-edge and may be obstructive to improvement of track density. A bump of 747 curve was produced in the case of little noise of EB. There is a close relationship between the shape of the 747 curve and EB noise.
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  • A Study on Burst Detector Using Parity Check Matrix of LDPC Code
    Yasuaki NAKAMURA, Seigo SATO, Yoshihiro OKAMOTO, Hisashi OSAWA, Hiroak ...
    Article type: Article
    Session ID: MMS2008-36
    Published: June 12, 2008
    Released on J-STAGE: September 20, 2017
    DOIhttps://doi.org/10.11485/itetr.32.23.0_35
    CONFERENCE PROCEEDINGS FREE ACCESS
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    It was difficult for the burst detector using the check matrix of LDPC code to detect a comparatively short burst. In this report, the improvement of detection ability for the short bit-flipping-like signal burst is studied. We obtain the burst detector resistant to the short burst by the improved moving average filter. The performance of the LDPC coding and iterative decoding system with the proposed burst detector is evaluated by computer simulation in a perpendicular magnetic recording channel with bit-flipping-like signal burst, and it is compared with that of the RS encoding and erasure correcting system. The results show that our LDPC coding and iterative decoding system becomes resistant to the short burst, and provides the better performance compared to the RS encoding and erasure correcting system for a burst length of 40 to 1200 bits.
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  • Relationship between crystal distortion and a magnetic anisotropy field of FeCoB films for soft magnetic underlayer
    Ken-ichiro Hirata, Atsuto Hashimoto, Toshimitsu Matsuu, Shigeki Nakaga ...
    Article type: Article
    Session ID: MMS2008-37
    Published: June 12, 2008
    Released on J-STAGE: September 20, 2017
    DOIhttps://doi.org/10.11485/itetr.32.23.0_41
    CONFERENCE PROCEEDINGS FREE ACCESS
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    The origin of high uniaxial magnetic anisotropy in FeCoB thin films were studied from the changes in FeCo crystal distortion and alignment. The films were prepared by facing targets sputtering and examined by X-ray diffraction (XRD) analysis. Preparation of Ru underlayer showed remarkably high anisotropy field H_k of 500 Oe. The Ru/FeCoB films revealed an oblique crystal growth and a preferential orientation. FeCo(110) lattice spacing had 0.5 % expansion along the easy axis and the strain indicated magnetoelastic energy E_<elastic> of 3.8×10^5 erg/cc exists along the easy axis. The estimated H_k from the Eelastic was 470 Oe which well corresponded with the measured H_k of 500 Oe. This indicates that the strain in FeCo lattice is the origin of the remarkably high magnetic anisotropy.
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  • Micromagnetic Simulations of Domain Wall Pinning in Recording Media
    Cho Mun LOKE, Simon GREAVES, Hiroaki MURAOKA
    Article type: Article
    Session ID: MMS2008-38
    Published: June 12, 2008
    Released on J-STAGE: September 20, 2017
    DOIhttps://doi.org/10.11485/itetr.32.23.0_47
    CONFERENCE PROCEEDINGS FREE ACCESS
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    Using a micro-magnetic model, cluster-pinned recording media consisting of clusters exchange-coupled to a continuous hard layer were modeled to investigate their suitability for high density data storage. The pinning field due to the clusters was determined by modeling domain-wall motion in the continuous layer. Larger clusters, a thinner continuous layer and increased saturation magnetization of the clusters all increased the pinning field. Different shapes of clusters had no effect on pinning field. Varying the cluster density, whilst maintaining the total surface area, significantly increased the pinning field once the cluster density dropped below a certain level. Simulations of recording demonstrated the feasibility of using domain wall pinning to control the written bit size in continuous media.
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  • [title in Japanese]
    Article type: Appendix
    Pages App1-
    Published: June 12, 2008
    Released on J-STAGE: September 20, 2017
    DOIhttps://doi.org/10.11485/itetr.32.23.0_App1
    CONFERENCE PROCEEDINGS FREE ACCESS
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  • [title in Japanese]
    Article type: Appendix
    Pages App2-
    Published: June 12, 2008
    Released on J-STAGE: September 20, 2017
    DOIhttps://doi.org/10.11485/itetr.32.23.0_App2
    CONFERENCE PROCEEDINGS FREE ACCESS
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  • [title in Japanese]
    Article type: Appendix
    Pages App3-
    Published: June 12, 2008
    Released on J-STAGE: September 20, 2017
    DOIhttps://doi.org/10.11485/itetr.32.23.0_App3
    CONFERENCE PROCEEDINGS FREE ACCESS
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