Masahiro Birukawa
Panasonic
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Publication
Featured researches published by Masahiro Birukawa.
Journal of Applied Physics | 2004
Motoyoshi Murakami; Masahiro Birukawa
The MsHc value of the TbFeCo magneto-optical medium was reported as a key factor in high-density recording. Microstructure control of the magnetic underlayer was identified as an effective method for increasing the value of MsHc. This article describes the relationship between the magnetic properties and microcolumnar structure, which depends on the growth process and sputtering conditions of the TbFeCo recording film and the layer structure. It has been found that the columnar structure of the film self grows under the low migration energy process without any magnetic underlayer. The process uses a target in-face type dc magnetron sputtering system with a low temperature substrate. The amount of sputtering gas was observed to play a dominant role in the self growth of the film. The coercivity Hc value increases by creating a microcolumnar structure, but the squareness ratio of the Kerr hysteresis loop of the film is reduced. And the perpendicular anisotropy constant Ku is decreased to less than 1×106 erg...
Japanese Journal of Applied Physics | 2003
Osamu Koyama; Koichiro Nishikawa; Yasushi Hozumi; Takaaki Ashinuma; Eiichi Fujii; Yasumori Hino; Masahiro Birukawa; Kenzo Ishibashi; Eiji Ueda; Toshio Matsumoto
Recording at a high density four times that of a current digital versatile disk random access memory (DVD-RAM) has been achieved by applying the domain wall displacement detection (DWDD) technology using a conventional optical head with the same wavelength of 660 nm and numerical aperture (NA) of 0.60 as those the DVD head. It has been confirmed by using an alternating sampled servo, laser annealing of the inter track area and partial response maximum likelihood (PRML) that a recording density of 15 Gbit/inch2 with a track pitch of 540 nm and bit length of 80 nm has sufficient system margins. A newly developed 1-bit-distributed address format has achieved a redundancy of 23%. Furthermore, the edge shift compensation technique has reduced the recording magnetic field. These indicate that a capacity of 3 GB on a two-inch-diameter disk is now available for mobile use. If applied to a digital video camera, one hour or more of moving-picture-experts-group-2 (MPEG2) video contents can be recorded at a bit rate of 6 Mbps.
Archive | 1999
Masahiro Birukawa; Yasumori Hino; Norio Miyatake
Archive | 1993
Masahiro Birukawa; Norio Miyatake; Yuuichi Fukamachi; Yoshihiko Kudoh; Yasumori Hino
Journal of Magnetism and Magnetic Materials | 2002
Takeo Ohta; Masahiro Birukawa; Noboru Yamada; Kazuyuki Hirao
Archive | 1987
Ryutaro Futakuchi; Masahiro Birukawa
Archive | 1992
Masahiro Birukawa; Norio Miyatake; Yasumori Hino
Archive | 1992
Yasumori Hino; Yoshihiko Kudoh; Masahiro Birukawa; Norio Miyatake
Archive | 1996
Masahiro Birukawa; Norio Miyatake; Yuuichi Fukamachi; Yoshihiko Kudoh; Yasumori Hino
Archive | 1995
Yuichi Fukamachi; Masahiro Birukawa