Hitachi, Ltd.

Emi Mangyo

Yuzuru Hosoe

Tomoo Yamamoto

Masaaki Futamoto

Nobuyuki Inaba

Masukazu Igarashi

Ichiro Tamai

Kazusuke Yamanaka

Yoshihiro Shiroishi

Kiwamu Tanahashi

Kazuetsu Yoshida

Yotsuo Yahisa

Shinji Narishige

Akira Ishikawa

Naoki Kodama

Futoshi Tomiyama

Katsuo Abe

Akira Osaki

A magnetic recording system high in S/N and low in bit error rate, capable of carrying out writing and reading of high recording density of at least 1 gigabit per 1 square inch and high in reliability can be realized by making the magnetic layer of the magnetic recording medium from a mixture comprising at least one non-magnetic compound selected from the group consisting of oxides and nitrides and a magnetic material comprising Co and Pt as main components and specifying the molar ratio of Pt to Co in the magnetic layer, and employing a magnetoresistive read back magnetic recording head.

Magnetic recording system and magnetic recording medium used therefor

In a magnetic recording system including magnetic recording media, a rotation driving unit for driving these magnetic recording media, read/write magnetic heads, driving apparatus for driving these read/write magnetic heads, and a read/write signal processing apparatus, a reading portion of the respective magnetic heads is arranged by a magnetoresistive head. The magnetic recording media are constructed of multi-layered magnetic media having a plurality of magnetic layers fabricated directly, or via underlayers on a non-magnetic disk substrate, and of non-magnetic intermediate layers arranged among these non-magnetic layers. Furthermore, one coercivity which is measured by applying a magnetic field along a circumferential direction of the magnetic recording media, is selected to be larger than the other coercivity which is measured by applying a magnetic field along a radial direction of the magnetic recording media, so that a higher signal-to-noise ratio is achieved, as compared with that of the conventional magnetic recording system. Since the thickness of the non-magnetic intermediate layers is smaller than or equal to 5 nm, and also the total layer is smaller than or equal to 5 nm, and also the total layer number of the plural magnetic layers is selected to be odd, better characteristics can be achieved. Accordingly, since the MTBF (Mean Time Before Failure) is longer than or equal to 0.15 million hours with high recording density, and the disk substrate and the magnetic head sliders can be mounted at high packaging density, a compact and high-capacity magnetic recording system can be obtained.

Multi-layered magnetic recording medium and magnetic recording system

A magnetic recording medium having a high coercivity and a high S/N ratio for high-density operation can include either a conductive or a nonconductive substrate. If the substrate is nonconductive, a conducting precoat layer is formed over the substrate. Further, an underlayer may be provided, over which a magnetic layer is formed by a bias sputtering method. The bias sputtering method may use Kr, Xe or Rn as a sputter gas, and employs a negative bias voltage. The magnetic recording medium has a product of remanent magnetization and magnetic layer thickness of 10-150 G.multidot..mu.m and a coercivity of 1600-4000 Oe. In combination with this magnetic recording medium, a large-capacity magnetic recording system has a write head that uses a magnetic material having a saturation magnetic flux density of more than 1.2 T in at least a part of the magnetic core; a read head utilizing the giant magnetoresistance effect; a signal processing circuit that utilizes maximum likelihood decoding; and circuits that correct for asymmetry of the reproduced signals from the magnetoresistive head. In addition, the flying height of the magnetic head slider is set to less than 0.05 .mu.m.

Magnetic recording medium containing heavy rare gas atoms, and a

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Emi Mangyo