Network


Latest external collaboration on country level. Dive into details by clicking on the dots.

Hotspot


Dive into the research topics where Masahiro Birukawa is active.

Publication


Featured researches published by Masahiro Birukawa.


Journal of Applied Physics | 2004

Magnetic properties and microcolumnar structure of a TbFeCo memory layer for high-density magneto-optical recording

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

Physical Characteristics and Format of a Two-Inch-Diameter Magneto-Optical Disk System with 3 GB Capacity

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

Method for reading magnetic super resolution type magneto-optical recording medium

Masahiro Birukawa; Yasumori Hino; Norio Miyatake


Archive | 1993

Optical recording disk, and recording/reading apparatus using same

Masahiro Birukawa; Norio Miyatake; Yuuichi Fukamachi; Yoshihiko Kudoh; Yasumori Hino


Journal of Magnetism and Magnetic Materials | 2002

Optical recording; phase-change and magneto-optical recording

Takeo Ohta; Masahiro Birukawa; Noboru Yamada; Kazuyuki Hirao


Archive | 1987

OPTICAL INFORMATION DEVICE

Ryutaro Futakuchi; Masahiro Birukawa


Archive | 1992

Abnormality detection of a recording medium in a magneto-optical recording system

Masahiro Birukawa; Norio Miyatake; Yasumori Hino


Archive | 1992

Magneto-optical recording medium and recording and reading out process using the same

Yasumori Hino; Yoshihiko Kudoh; Masahiro Birukawa; Norio Miyatake


Archive | 1996

Rewritable disk-shaped optical recording medium

Masahiro Birukawa; Norio Miyatake; Yuuichi Fukamachi; Yoshihiko Kudoh; Yasumori Hino


Archive | 1995

Magneto-optical recording medium for magnetically induced super resolution

Yuichi Fukamachi; Masahiro Birukawa

Collaboration


Dive into the Masahiro Birukawa's collaboration.

Researchain Logo
Decentralizing Knowledge