Hitachi, Ltd.

Hitachi Maxell, Limited

Hitachi Global Storage Technologies Japan, Ltd.

Hitachi Global Storage Technologies

Masaaki Futamoto

Yukio Honda

Yoshiyuki Hirayama

Nobuyuki Inaba

Kazuetsu Yoshida

Yoshibumi Matsuda

Mikio Suzuki

Yoshinori Miyamura

Hisashi Takano

Kyo Akagi

Fumio Kugiya

Takeshi Nakao

Hirotsugu Fukuoka

Takayuki Munemoto

Tokuho Takagaki

Yuzuru Hosoe

Tomoo Yamamoto

Kazuo Shiiki

Isamu Yuito

Toshio Kobayashi

Hideo Tanabe

Naoki Koyama

Masahiro Kitada

Ryoichi Nakatani

Noboru Shimizu

Eijin Moriwaki

Kenya Ito

Kazusuke Yamanaka

Atsushi Kikugawa

Kiwamu Tanahashi

Yasutaro Uesaka

Akira Ishikawa

Atsushi Nakamura

Masukazu Igarashi

Shinji Narishige

Kenji Furusawa

Ushio Kawabe

Teruaki Takeuchi

Takanobu Takayama

Emi Mangyo

Hiroyuki Suzuki

Yoshihiro Shiroishi

Yohji Maruyama

Hisashi Kimura

Yoshiaki Kawato

Ichiro Tamai

Kazumasa Takagi

Kazuhiro Nakamoto

Shigeyuki Hosoki

Kaori Suzuki

Takashi Nishimura

Chiseki Haginoya

Hideo Matsuyama

Atsushi Kikukawa

Motoyasu Terao

Yoshimi Kawanami

Tohru Ishitani

Shinichiro Saito

Yasushi Miyauchi

Hideo Fujiwara

Hideki Sawaguchi

Fumiyoshi Kirino

Kenji Mori

Masahiko Hiratani

Keikichi Andoo

Hifumi Tamura

Hiroyuki Awano

Hajime Aoi

Toshiyuki Aida

Masahiko Takahashi

Yasuhide Ouchi

Toshio Niihara

Tokuumi Fukazawa

Heigo Ishihara

Yosuke Seo

Norikazu Tsumita

Hideo Daimon

Katsuki Miyauchi

Shigehiko Yamamoto

Hiroyuki Kataoka

Osamu Kitakami

Tsutomu Komoda

Reiji Tamura

Seiichi Asada

Makoto Aihara

Shigenori Okamine

Yuuichi Madokoro

Toyoji Okuwaki

Hitoshi Iwata

Kazushige Imagawa

Selichi Asada

Takeshi Nakano

A perpendicular magnetic recording medium which has been improved to be suitable for high-density magnetic recording and a magnetic recording apparatus using the medium are provided. The magnetic back film of a dual-layer perpendicular recording medium is caused to be constituted by a plurality of layers, and a keeper layerfor keeping perpendicular magnetization and layersandfor improving the recording efficiency of a recording head are functionally separated from one another. Further, the magnetization orientations of the soft magnetic films excluding the keeper layer are defined to be in the circumferential direction of the disk, whereby the frequency of occurrence of noise is decreased.

Perpendicular magnetic recording media, magnetic recording apparatus

The present invention is directed to carrying out a high density magnetic recording to a material having a large coercive force by perpendicular magnetic recording head. By giving a patterning onto a soft magnetic under layer of a perpendicular two-layer recording media in sync with a period of a recording bit, a magnetic field from a write head can be allowed to converge to a soft magnetic column. Therefore, a magnetization reversal of the magnetic recording media material having a large anisotropic constant becomes possible, and then a high density magnetic recording can be achieved.

Magnetic recording media and method of forming them

An improved perpendicular magnetic recording medium and an improved magnetic storage apparatus are provided, which are suitable for high speed and high density magnetic recording. A magnetic under layer of a two-layered perpendicular magnetic recording medium includes three layers: a ferromagnetic layer; a non-magnetic layer; and a ferromagnetic layer, wherein the ferromagnetic layers are antiferromagnetically coupled with each other, thereby preventing a magnetic flux from a magnetic wall in a magnetic under layer from entering a read back head.

Perpendicular magnetic recording medium and magnetic storage apparatus

The magnetoresistance effect element is of a multilayered structure having at least magnetic layers and an intermediate layer of an insulating material, a semiconductor or an antiferromagnetic material against the magnetic layers, and the magnetoresistance effect element has terminals formed at least on the opposite magnetic layers, respectively, so that a current flows in the intermediate layer. The film surfaces of all the magnetic layers constituting the magnetoresistance effect element are opposed substantially at right angles to the recording surface of a magnetic recording medium. Therefore, the area of the magnetic layers facing the recording surface of the magnetic recording medium can be extremely reduced, and thus the magnetic field from a very narrow region of the high-density recorded magnetic recording medium can be detected by the current which has a tunneling characteristic and passes through the intermediate layer.

Method for manufacturing magnetic head device

A magnetic recording medium having a substrate, an under-layer formed on the substrate, a magnetic layer formed on the substrate and a protective layer formed on the magnetic layer. The magnetic layer comprises Co, Cr and Pt with a thickness being from 10 nm to 22 nm. Further, a coercivity of the magnetic layer is not less than 2000 Oe, and a fluctuation field of magnetic viscosity at a field strength equal to remanence coercivity or coercivity is not less than 30 Oe.

Magnetic recording medium and magnetic recording and reproducing apparatus

A double layer perpendicular magnetic recording medium having a high medium S/N ratio at a recording density of 50 Gb/inor higher and a magnetic storage apparatus with a lower error rate and excellent reliability are provided. In a perpendicular magnetic recording medium in which a soft magnetic underlayer, an intermediate layer, and a perpendicular magnetic recording layerare sequentially formed on a substrate, the intermediate layeris made to be a non-magnetic amorphous alloy, in which Ni is a main component and Zr is contained, and the soft magnetic underlayeris constituted of ferromagnetic nan-crystals precipitated by annealing.

Perpendicular magnetic recording media and magnetic storage

The present invention is directed to-carrying out a high density magnetic recording to a material having a large coercive force by perpendicular magnetic recording head. By giving a patterning onto a soft magnetic under layer of a perpendicular two-layer recording media in sync with a period of a recording bit, a magnetic field from a write head can be allowed to converge to a soft magnetic column. Therefore, a magnetization reversal of the magnetic recording media material having a large anisotropic constant becomes possible, and then a high density magnetic recording can be achieved.

Magnetic apparatus with perpendicular recording medium and head having multilayered reproducing element using tunneling effect

An object is to automatically detect the positions of spike noise, create a distribution diagram, and perform pass/fail decisions. The cross-correlation function of the signal waveform from a magnetic headand a reference waveform simulating spike noise is used in extraction of spike noise. The number of peaks in the cross-correlation function exceeding a threshold value is counted, and quantitative evaluation of spike noise is performed.

Method for testing or recording servo signal on perpendicular magnetic recording media

The present invention relates to perpendicular magnetic recording media using a ferromagnetic film provided with perpendicular magnetic anisotropy for a recording layer and a magnetic recording apparatus using the media, and the object is to provide the perpendicular magnetic recording media which are excellent in signal to noise ratio (S/N) in a large recording density region, which are stable against thermal fluctuation and which can be easily manufactured, and the magnetic recording apparatus using the media. The representative perpendicular magnetic recording media according to the invention include a glass substrate, a first recording layer which is provided on the substrate via an underlayer, which has perpendicular magnetic anisotropy and the magnitude of magnetic exchange interaction between grains of which is substantially zero and a second recording layer which is laminated on the first recording layer, which is provided with perpendicular magnetic anisotropy and the magnetic exchange interaction between grains of which is larger than that of the first recording layer.

Perpendicular-magnetic recording media and magnetic recording apparatus

An ferromagnetic thin film is used to provide a magnetic recording medium whose noise is low and whose S/N value is high. The ferromagnetic thin film as the magnetic film of the magnetic recording medium is such that the fluctuation field of magnetic viscosity at 25&#xb0; C. at the field strength equal to remanence coercivity or coercivity is not less than 15 oersteds and the coercivity is not less than 2000 oersteds.

Magnetic recording medium possessing a fluctuation field of not less than 30 Oe

Perpendicular magnetic recording medium and magnetic recording apparatus

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Shiroyama, Japan

Masaaki Futamoto