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Harukazu Miyamoto - One of the best experts on this subject based on the ideXlab platform.
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Read-head Conditions for Obtaining Areal Recording Density of 5.8 Tbit/in.2 on a Bit-Patterned Medium
Japanese Journal of Applied Physics, 2013Co-Authors: Fumiko Akagi, Junko Ushiyama, Harukazu Miyamoto, Seiichi MitaAbstract:The optimum magneto-resistive read-head (MR head) conditions, namely, read track width (TWR) and shield gap (Gs), with a bit-patterned medium (BPM) for areal Recording Density of 5.8 Tbit/in.2 were determined by analytical calculation. Signal-to-noise ratio at a linear Recording Density of 1124 kfci (SNR1124kfci) and crosstalk were calculated in consideration of head noise, and optimum TWR and Gs were obtained from the calculation results. The effect of intertrack interference cancellation (ITIC) was investigated by using a signal-processing simulator. The investigation shows that intertrack interference cancellation decreases bit error rate. Moreover, to obtain bit error rate of 10-3 and SNR1124kfci of 14 dB, TWR can be increased to about two times track pitch for Gs of 15 nm. For obtaining SNR1124kfci of 14 dB, TWR should be 15 nm at σ/Dave of 5% or TWR should be 11 nm at σ/Dave of 10%. These results demonstrate that ITIC effectively decreases bit error rate and thus contributes to attaining areal Recording Density of 5.8 Tbit/in.2.
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Head and Granular Media for Thermally Assisted Magnetic Recording for Recording Density of 6 Tb/in $^{2}$
IEEE Transactions on Magnetics, 2013Co-Authors: Fumiko Akagi, Junko Ushiyama, Ayano Ando, Harukazu MiyamotoAbstract:Optimum structural dimensions and characteristics of a granular thermally-assisted-magnetic-Recording (TAMR) medium for a Recording Density of more than 6 Tb/in2 were investigated by using optical, thermal, and Landau-Lifshitz-Gilbert (LLG) simulators. A sharp thermal profile in the medium could be obtained by using a heat-sink layer with heat conductivity greater than 100 W/m K. The ratio of in-plane κ to out-of-plane κ(κxy/κg) of the Recording layer and thickness (TmMgO) of the MgO layer should both be decreased. The targets for magnetic-write width (MWW) and signal-to-noise ratio (SNR) are 18 nm and 12 dB for a Recording Density greater than 6 Tb/in2, respectively. In the case of TmMgO of 12 nm, the conditions for achieving these targets are ΔT of 450 K and Heff of 1.36 MA/m. In the case of TmMgO of 5 nm, the conditions are ΔT of 600 K and Heff of 1.4 MA/m (namely, MWW of 18 nm and Recording Density of 6.0 Tb/in2); ΔT of 550 K and Heff of 1.48 MA/m (namely, MWW of 16.5 nm and Recording Density of 6.5 Tb/in2); and ΔT of 500 K and Heff of 1.58 MA/m (namely, MWW of 15.0 nm and Recording Density of 7.2 Tb/in2). It is also clear that the thermal profile is a determinant factor in MWW.
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Thermally assisted magnetic Recording with bit-patterned media to achieve areal Recording Density beyond 5 Tb/in2
Journal of Magnetism and Magnetic Materials, 2012Co-Authors: Fumiko Akagi, Junko Ushiyama, Masaki Mukoh, Masafumi Mochizuki, Takuya Matsumoto, Harukazu MiyamotoAbstract:Abstract Thermally assisted magnetic Recording (TAR) with bit-patterned media was investigated by micromagnetic simulation. The media were assumed to be FePt layers. The effective head-field margin as well as the increase in temperature margin and down-track shift margin was investigated. Conditions of the head and medium that lead to a Recording Density beyond 5 Tb/in 2 were proposed.
Fumiko Akagi - One of the best experts on this subject based on the ideXlab platform.
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Read-head Conditions for Obtaining Areal Recording Density of 5.8 Tbit/in.2 on a Bit-Patterned Medium
Japanese Journal of Applied Physics, 2013Co-Authors: Fumiko Akagi, Junko Ushiyama, Harukazu Miyamoto, Seiichi MitaAbstract:The optimum magneto-resistive read-head (MR head) conditions, namely, read track width (TWR) and shield gap (Gs), with a bit-patterned medium (BPM) for areal Recording Density of 5.8 Tbit/in.2 were determined by analytical calculation. Signal-to-noise ratio at a linear Recording Density of 1124 kfci (SNR1124kfci) and crosstalk were calculated in consideration of head noise, and optimum TWR and Gs were obtained from the calculation results. The effect of intertrack interference cancellation (ITIC) was investigated by using a signal-processing simulator. The investigation shows that intertrack interference cancellation decreases bit error rate. Moreover, to obtain bit error rate of 10-3 and SNR1124kfci of 14 dB, TWR can be increased to about two times track pitch for Gs of 15 nm. For obtaining SNR1124kfci of 14 dB, TWR should be 15 nm at σ/Dave of 5% or TWR should be 11 nm at σ/Dave of 10%. These results demonstrate that ITIC effectively decreases bit error rate and thus contributes to attaining areal Recording Density of 5.8 Tbit/in.2.
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Head and Granular Media for Thermally Assisted Magnetic Recording for Recording Density of 6 Tb/in $^{2}$
IEEE Transactions on Magnetics, 2013Co-Authors: Fumiko Akagi, Junko Ushiyama, Ayano Ando, Harukazu MiyamotoAbstract:Optimum structural dimensions and characteristics of a granular thermally-assisted-magnetic-Recording (TAMR) medium for a Recording Density of more than 6 Tb/in2 were investigated by using optical, thermal, and Landau-Lifshitz-Gilbert (LLG) simulators. A sharp thermal profile in the medium could be obtained by using a heat-sink layer with heat conductivity greater than 100 W/m K. The ratio of in-plane κ to out-of-plane κ(κxy/κg) of the Recording layer and thickness (TmMgO) of the MgO layer should both be decreased. The targets for magnetic-write width (MWW) and signal-to-noise ratio (SNR) are 18 nm and 12 dB for a Recording Density greater than 6 Tb/in2, respectively. In the case of TmMgO of 12 nm, the conditions for achieving these targets are ΔT of 450 K and Heff of 1.36 MA/m. In the case of TmMgO of 5 nm, the conditions are ΔT of 600 K and Heff of 1.4 MA/m (namely, MWW of 18 nm and Recording Density of 6.0 Tb/in2); ΔT of 550 K and Heff of 1.48 MA/m (namely, MWW of 16.5 nm and Recording Density of 6.5 Tb/in2); and ΔT of 500 K and Heff of 1.58 MA/m (namely, MWW of 15.0 nm and Recording Density of 7.2 Tb/in2). It is also clear that the thermal profile is a determinant factor in MWW.
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Thermally assisted magnetic Recording with bit-patterned media to achieve areal Recording Density beyond 5 Tb/in2
Journal of Magnetism and Magnetic Materials, 2012Co-Authors: Fumiko Akagi, Junko Ushiyama, Masaki Mukoh, Masafumi Mochizuki, Takuya Matsumoto, Harukazu MiyamotoAbstract:Abstract Thermally assisted magnetic Recording (TAR) with bit-patterned media was investigated by micromagnetic simulation. The media were assumed to be FePt layers. The effective head-field margin as well as the increase in temperature margin and down-track shift margin was investigated. Conditions of the head and medium that lead to a Recording Density beyond 5 Tb/in 2 were proposed.
Hiroyuki Osaki - One of the best experts on this subject based on the ideXlab platform.
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Recent research of tape/drive tribology
Tribology International, 2003Co-Authors: Hiroyuki OsakiAbstract:Decreasing track width and tape thickness to increase the volumetric Recording Density of helical scan-tape-drive systems, which is suitable for higher volumetric Recording Density, will result in the failure of tracking. The displacement of tape forwarding position, which causes failure of tracking, is caused by static friction coefficient between a tape and a roller guide. It was found that surface roughness and materials of roller guides are very important to reduce static friction coefficient.
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Flexible media — recent developments from the tribology point of view
Tribology International, 2000Co-Authors: Hiroyuki OsakiAbstract:With the increase in the Recording Density of hard disk systems, the demand on the increase in the data Recording capacity of tape drive systems as back-up systems is increasing. One of the advantages of the tape drive systems is high volumetric Recording Density, which is obtained by high areal Recording Density and thin tapes. The areal Recording Density can be increased by introducing high performance tapes, such as metal evaporated tapes, with superior magnetic characteristics and smooth magnetic surface to reduce the spacing loss. However, a smoother surface often produces a higher friction coefficient, which could cause tape damage by rotary heads and unstable tape runnability in the tape drives. Adoption of MR heads to tape drive systems is also effective in increasing the areal Recording Density. However, the wear allowance of the MR heads (shield type) is much smaller than that of the inductive heads. Thinner tapes show lower mechanical stiffness in general, which could cause damage to tape edges easily during tape transportation. In the second or later generation of tape drive systems, a thinner tape is often introduced. These thinner tapes should also have the interchangeability of the original thickness tape. New materials for a base film, such as PEN (polyethylene naphthalate) or aramid in which the elastic moduli are larger than those of PET, are required for thinner tapes. It was found that these side effects by the increase in the volumetric Recording Density can be improved by tribology. The tribological improvements from the drive design side is very important, as well as from the tape design side.
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Tribology of metal evaporated tapes—for improvement of Recording Density
Tribology International, 1998Co-Authors: Hiroyuki OsakiAbstract:Increased Recording Density in video tape recorders and tape drives for data storage has been achieved by the increase in areal Recording Density and the decrease in tape thickness. Areal Recording Density can be increased by introducing high performance tapes, like metal evaporated tapes, with superior magnetic characteristics and smooth magnetic surfaces to reduce the spacing loss. However smoother surfaces often produce a higher friction coefficient, which could result in tape damage by the scanning heads and unstable runnability of tapes in VTRs or tape drives. Also thinner tapes show lower mechanical stiffness in general, which could result in damage of the tape edges during tape transportation. Superior durability and runnability are thus required of high performance tape in addition to magnetic characteristics, in spite of the trend towards smoother surface and thinner tapes. Therefore the development of practical new magnetic tapes requires research into their tribology. It was found that the durability and runnability of metal evaporated tapes with smoother surfaces can be improved by DLC coating, and that the edge damage of thinner tapes can be eliminated by decreasing the static friction coefficient, but not the kinetic one. Though the durability and the runnability of metal evaporated tapes themselves have been improved from the tape design point of view, as mentioned above, further improvement may be expected by integrating tape design with that of the VTR/tribo-elements tape drive design and thus further increasing Recording Density in the future.
Masahiro Irie - One of the best experts on this subject based on the ideXlab platform.
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High-Density Optical Memory and Ultrafine Photofabrication
Nano-Optics, 2002Co-Authors: Masahiro IrieAbstract:Optical Recording uses focused or minimal size laser light to effect some optical property change in Recording media, which is subsequently read back by the laser. Various approaches have been proposed to increase the Recording Density of optical memories: decreasing the Recording mark size by using short-wavelength lasers, three-dimensional Recordings, and near-field optical Recording. Among them the most promising approach is a near-field optical Recording. Recording Density in conventional optical Recording is limited by the diffractive limit of light and the numerical aperture of the lens. Therefore, the mark size cannot be reduced to less than the wavelength of light. In near-field optical Recording, in contrast, the size depends only on the diameter of the probe tip aperture. Therefore, the Recording Density can be increased at will, in principle, if a small aperture tip is available.
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Theoretical study of the Recording Density limit of a near-field photochromic memory
Journal of the Optical Society of America B, 1998Co-Authors: Tsuyoshi Tsujioka, Masahiro IrieAbstract:The Recording Density limit of a near-field optical memory that uses a photochromic medium was theoretically studied by use of Shannon’s information theory. Shot noise and material noise were taken into account in the analysis of the signal-to-noise ratio. The conventional Recording Density limit, which is defined by the inverse of the minimum recorded mark area, and Shannon’s Recording Density limit were evaluated. The conventional Recording Density limit was 1011–1012 bits/cm2, and Shannon’s Recording Density limit was 1012–1013 bits/cm2.
Junko Ushiyama - One of the best experts on this subject based on the ideXlab platform.
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Read-head Conditions for Obtaining Areal Recording Density of 5.8 Tbit/in.2 on a Bit-Patterned Medium
Japanese Journal of Applied Physics, 2013Co-Authors: Fumiko Akagi, Junko Ushiyama, Harukazu Miyamoto, Seiichi MitaAbstract:The optimum magneto-resistive read-head (MR head) conditions, namely, read track width (TWR) and shield gap (Gs), with a bit-patterned medium (BPM) for areal Recording Density of 5.8 Tbit/in.2 were determined by analytical calculation. Signal-to-noise ratio at a linear Recording Density of 1124 kfci (SNR1124kfci) and crosstalk were calculated in consideration of head noise, and optimum TWR and Gs were obtained from the calculation results. The effect of intertrack interference cancellation (ITIC) was investigated by using a signal-processing simulator. The investigation shows that intertrack interference cancellation decreases bit error rate. Moreover, to obtain bit error rate of 10-3 and SNR1124kfci of 14 dB, TWR can be increased to about two times track pitch for Gs of 15 nm. For obtaining SNR1124kfci of 14 dB, TWR should be 15 nm at σ/Dave of 5% or TWR should be 11 nm at σ/Dave of 10%. These results demonstrate that ITIC effectively decreases bit error rate and thus contributes to attaining areal Recording Density of 5.8 Tbit/in.2.
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Head and Granular Media for Thermally Assisted Magnetic Recording for Recording Density of 6 Tb/in $^{2}$
IEEE Transactions on Magnetics, 2013Co-Authors: Fumiko Akagi, Junko Ushiyama, Ayano Ando, Harukazu MiyamotoAbstract:Optimum structural dimensions and characteristics of a granular thermally-assisted-magnetic-Recording (TAMR) medium for a Recording Density of more than 6 Tb/in2 were investigated by using optical, thermal, and Landau-Lifshitz-Gilbert (LLG) simulators. A sharp thermal profile in the medium could be obtained by using a heat-sink layer with heat conductivity greater than 100 W/m K. The ratio of in-plane κ to out-of-plane κ(κxy/κg) of the Recording layer and thickness (TmMgO) of the MgO layer should both be decreased. The targets for magnetic-write width (MWW) and signal-to-noise ratio (SNR) are 18 nm and 12 dB for a Recording Density greater than 6 Tb/in2, respectively. In the case of TmMgO of 12 nm, the conditions for achieving these targets are ΔT of 450 K and Heff of 1.36 MA/m. In the case of TmMgO of 5 nm, the conditions are ΔT of 600 K and Heff of 1.4 MA/m (namely, MWW of 18 nm and Recording Density of 6.0 Tb/in2); ΔT of 550 K and Heff of 1.48 MA/m (namely, MWW of 16.5 nm and Recording Density of 6.5 Tb/in2); and ΔT of 500 K and Heff of 1.58 MA/m (namely, MWW of 15.0 nm and Recording Density of 7.2 Tb/in2). It is also clear that the thermal profile is a determinant factor in MWW.
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Thermally assisted magnetic Recording with bit-patterned media to achieve areal Recording Density beyond 5 Tb/in2
Journal of Magnetism and Magnetic Materials, 2012Co-Authors: Fumiko Akagi, Junko Ushiyama, Masaki Mukoh, Masafumi Mochizuki, Takuya Matsumoto, Harukazu MiyamotoAbstract:Abstract Thermally assisted magnetic Recording (TAR) with bit-patterned media was investigated by micromagnetic simulation. The media were assumed to be FePt layers. The effective head-field margin as well as the increase in temperature margin and down-track shift margin was investigated. Conditions of the head and medium that lead to a Recording Density beyond 5 Tb/in 2 were proposed.