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Volume 22, Issue S_3_PMRS_98
Displaying 1-12 of 12 articles from this issue
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Naoki HONDA, Takanori KIYA, Jun ARIAKE, Lianjun WU, Kazuhiro OUCHI1999 Volume 22 Issue S_3_PMRS_98 Pages S3_1-4
Published: 1999
Released on J-STAGE: December 15, 2011
JOURNAL OPEN ACCESSDesign concept for low noise perpendicular recording media is proposed based on an in-bit reversed domain model. Although smaller reversed domains and a higher SQ⊥ are expected to be essential for low noise property, substantial noise is observed for films with SQ⊥=1 due to reversed domains formed in the recording process. The noise is decreased for films with a smaller M-H loop slope. It was indicated that the loop slope has opposite effects on the noise and recording properties of the media. Improvement in the recording head and realization of new low noise media with a square M-H loop are the present issues.View full abstractDownload PDF (749K) -
Y. Hirayama, Y. Honda, K. Ito, T. Takeuchi, M. Futamoto1998 Volume 22 Issue S_3_PMRS_98 Pages S3_5-8
Published: 1998
Released on J-STAGE: December 15, 2011
JOURNAL OPEN ACCESSThickness dependence of noise characteristics and thermal decay have been investigated for CoCr19Pt10 and CoCr17Ta4 single-layer perpendicular media. The thermal stability of recorded bit is improved by making Mr/Ms ratio close to 1. The maximum S/N ratios are observed for both-type media when the recording layer thickness is around 25 um. Good correlation between the magnetic domain size and the noise value shows that it is necessary to decrease the magnetic domain size to reduce the medium noise.View full abstractDownload PDF (628K) -
Hirotaka HOKKYO, Shinzo TSUBOI, Norikazu OHSHIMA, Katsumichi TAGAMI1998 Volume 22 Issue S_3_PMRS_98 Pages S3_9-12
Published: 1998
Released on J-STAGE: December 15, 2011
JOURNAL OPEN ACCESSDouble-layer media with single pole heads are the ideal way of perpendicular magnetic recording. However, unstableness of recorded magnetization originating from magnetic domains of underlayers have not been settled. We investigated signal stability of the media using NiFe underlayers and the media using FeSiAl underlayers, which take the diferent magnetization process from NiFe underlayers. The results show that the media using FeSiAl showed better stability of recorded magnetization than those using NiFe.View full abstractDownload PDF (771K) -
Kenji Sato, Yuki Yoshida, Chiaki Okuyama, Iwao Okamoto, Masayoshi Shin ...1998 Volume 22 Issue S_3_PMRS_98 Pages S3_13-16
Published: 1998
Released on J-STAGE: December 15, 2011
JOURNAL OPEN ACCESSDemagnetizing Fields in recorded bits accelerated thermal decay of data output in magnetic recording media. The spread of transition area also promotes the reduction of obtained data output. We compared the time dependencies of data output at several recording densities when a spin stand was used with the time dependencies of the remanent magnetization in various applied fields. The various applied fields corresponded to the demagnetizing fields in the recorded bits at their respective recording densities. We have experimentally confirmed that reproduced output reduction can explained by considering the degradation of both magnetization and transition length for longitudinal recording media. We have also experimentally confirmed that output reduction can be reduced by putting a soft magnetic underlayer for perpendicular media.View full abstractDownload PDF (702K)
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S. Onodera, H. Wako, T. Samoto, T. Kawana, Y. Ikeda, T. Ozue1998 Volume 22 Issue S_3_PMRS_98 Pages S3_17-20
Published: 1998
Released on J-STAGE: December 15, 2011
JOURNAL OPEN ACCESSWe investigated thin metal evaporated tapes with MR heads in a helical scanning system, trying to achive a high recording density. We found that ME tape can realize low Mr•t values by changing the amount of oxygen during evaporation and thickness of magnetic layer to obtain a low noise media. Thin ME tapas are suitable media for high sensitivity heads such as MR heads.View full abstractDownload PDF (719K) -
S. YAMAMOTO, T. SANTOKI, H. KURISU, M. MATSUURA, J. KOUJIMA, K. NAKATA ...1998 Volume 22 Issue S_3_PMRS_98 Pages S3_21-25
Published: 1998
Released on J-STAGE: December 15, 2011
JOURNAL OPEN ACCESSIn the fabrication process of Co-γFe2O3/NiO thin film recording disks, new oxidization method using oxygen ions in a plasma was proposed to transform a CoO-Fe3O4 film to a Co-γFe2O3 film. Remarkably effective oxidization was achieved by utilizing oxygen ions produced in an electron-cyclotron-resonance microwave plasma, promotion of oxygen ion generation by Penning ionization effect using metastable He atoms, and neutralization for preventing static electricity of samples. This plasma oxidization method shortened the oxidization processing time to 10 seconds and lowered the process temperature to 150 °C for the 20nm thick CoO-Fe3O4 films. Almost same recording characteristics was obtained between the Co-γFe2O3/NiO disks prepared by the plasma oxidization method and a conventional heat oxidization method in air.View full abstractDownload PDF (713K) -
N. Matsuda, J. Feng, K. Watanabe, T. Murakoso, S. Nakagawa, M. Naoe1998 Volume 22 Issue S_3_PMRS_98 Pages S3_27-31
Published: 1998
Released on J-STAGE: December 15, 2011
JOURNAL OPEN ACCESSIn the first half of this work, a magnetoplumbite-type of Ba ferrite (BaM) layers were deposited from BaFe11O19-y targets and BaFe13O19-y ones on a ZnO(001) underlayer in a gas mixture of Ar, Xe, and O2 using facing targets sputtering apparatus. It was clarified that a stoichiometric composition is necessary for preparing Ba ferrite films with large saturation magnetization 4πMs and excellent perpendicular anisotropy. Ba ferrite films deposited at optimum conditions exhibited large 4πMs of 4.7 kG and high perpendicular coercivity Hc⊥ of 2.4 kOe and low in-plane one Hc// of 0.2 kOe even when substrate temperature Ts was as low as 475°C. In the latter half of this work, Al substituted Ba ferrite films were deposited from BaFe11Al1O19-y targets and BaFe10Al2O19-y ones on Pt (111) underlayer for increasing Hc⊥ and perpendicular squareness Sc⊥. Although 4πMs decreased with increase of substitution amount x, Hc⊥ increased even for as-deposited films. S⊥ increased after annealing at 850-900°C for 15 min in air the maximum S⊥ of 0.91 was attained for films deposited from BaFe10Al2O19-y target.View full abstractDownload PDF (622K)
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Hisashi OSAWA, Yoshihiro OKAMOTO, Hidetoshi SAITO, Hiroaki MURAOKA, Yo ...1998 Volume 22 Issue S_3_PMRS_98 Pages S3_33-37
Published: 1998
Released on J-STAGE: December 15, 2011
JOURNAL OPEN ACCESSThe partial response maximum-likelihood (PRML) systems for perpendicular magnetic recording using an MR head and a double-layered medium are studied. The bit error rate performance of PRML systems characterized by the polynomials with the positive coefficients and conventional PRML systems with the negative coefficients for the 16/17(0,6/6) code is evaluated by computer simulation. Among PRML systems discussed in this study, PR(1,2,2,1)ML exhibits the best performance and improves the SNR by about 6.2dB over that of EPR4ML at a bit error rate of 10-4 and a normalized linear density of 2.5. At high linear density, the performance of PR(1,2,3,2,1) ML for the 16/17(0,6/6) code is superior to that of PR(1,2,3,2,1)ML for the (1,7)RLL code.View full abstractDownload PDF (599K) -
Akira Iketani, Masaaki Kobayashi, Saburo Tazaki1998 Volume 22 Issue S_3_PMRS_98 Pages S3_39-46
Published: 1998
Released on J-STAGE: December 15, 2011
JOURNAL OPEN ACCESSThis paper describes a systematic construction method of Run Length Limited (RLL) codes for the purpose of getting higher recording density realized. The continuous number of a binary value in the RLL code is restricted to not less than d and not greater than k in NRZL notation by converting a data word of m-bit to a codeword of n-bit. This method comprises; a) equations for calculating the number of the codewords; b) rules for selecting codewords; c) rules for concatenating the codewords. Various kinds of fixed length or variable length RLL codes have been gotten under the conditions of d= 1, 2, ···, 6, k= d+1, ···, 15 in NRZL expression, and n= d+1, ···, 32.View full abstractDownload PDF (826K)
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H. Muraoka, K. Miura, Y. Sugita, Y. Nakamura1998 Volume 22 Issue S_3_PMRS_98 Pages S3_47-52
Published: 1998
Released on J-STAGE: December 15, 2011
JOURNAL OPEN ACCESSDigital signal evaluation for a thin-film single-pole head and double layer perpendicular disk was carrited out with an error rate tester. An AMR head was used as a reading head. The channel of the tester was the PR4ML with the 8/9 endec. Waveform for the MR head was transformed with a differentiator consisted of passive LCR circuitry and high speed linear amplifier. A D50 of 185 kFRPI, a PW50 of 130 nm, and an NLTS at 300 kFRPI were measured. A byte error rate of 10-6 was obtained at 310 kFRPI for a read trackwidth of 1.4 μm.View full abstractDownload PDF (867K) -
Yoshio Suzuki1998 Volume 22 Issue S_3_PMRS_98 Pages S3_53-56
Published: 1998
Released on J-STAGE: December 15, 2011
JOURNAL OPEN ACCESSA new method of field calculation for head-medium systems was developed. The new method is accurate, quick to execute, and compact, without requirement for a special mesh making process. The new method can be applied to various problems including, the medium field and the self demagnetizing field calculations for MR heads, and the head medium interaction calculation in the recording process.View full abstractDownload PDF (555K) -
Tatsuya Kurioka, Junji Numazawa1998 Volume 22 Issue S_3_PMRS_98 Pages S3_57-61
Published: 1998
Released on J-STAGE: December 15, 2011
JOURNAL OPEN ACCESSIn the age of digital multimedia, demand is bound to rise for television Home Servers that automatically record a viewer's favorite programs so that he/she can watch them at any time. We have developed an experimental Home Server on which a recorded HDTV program can be played back while recording another digital HDTV program. Using a new HSMS (hierarchical storage management system) we proposed, it was able to store HDTV programs for 4 hours and was as small as thickness of flat displays. This paper describes the outline of the experimental system and aims to clarify the recording requirements for hard disks and tapes by examining the read/write performance of hard disks on multi-channels and the nonlinear accessibility to programs recorded on tapes.View full abstractDownload PDF (724K)
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