Hitachi, Ltd.

Hitachi Maxell, Limited

Hitachi Global Storage Technologies Japan, Ltd.

Yasutaro Uesaka

Masaaki Futamoto

Yuzuru Hosoe

Hideo Fujiwara

Yoshibumi Matsuda

Nobuyuki Inaba

Tomoo Yamamoto

Shinji Narishige

Kenji Furusawa

Kazusuke Yamanaka

Iwao Matsuyama

Hajime Fukke

Naoki Kodama

Masayuki Katsumoto

Katsuyoshi Chiba

Yukio Honda

Kazuo Shiiki

Kazuetsu Yoshida

Heigo Ishihara

Sadao Hishiyama

Kazuo Ichino

Michiyasu Itoh

Yukio Ichinose

Hitoshi Inoue

Yoshihiro Shiroishi

Hideo Tanabe

Sadayasu Ueno

Masahiro Kitada

Noboru Shimizu

Tsuneo Suganuma

Motoo Akagi

Fumiyuki Inose

Osamu Kitakami

Isamu Orita

Satoshi Taniguchi

Tsutomu Kobayashi

Hisashi Thuruoka

Yoshiharu Terada

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

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

A thin film magnetic recording medium including a magnetic layer having a fluctuation field defined as S/X , where S is magnetic viscosity and X is irreversible susceptibility X . The fluctuation field of the magnetic layer is not less than 15 oersteds.

Magnetic recording medium and magnetic recording and reproducing apparatus wherein the magnetic layer has a fluctuation of field; A or Hf of not less than 30 Oersteds

A ferromagnetic thin film is used to provide a magnetic recording medium whose noise is low and whose S/N 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&deg; 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 thin film magnetic recording medium

A method for manufacturing a magnetic paint by mixing a resin composition powder as a dispersing binder for a magnetic powder with the magnetic powder, or together with a filler, and grinding the mixture under a high shear stress is disclosed. A magnetic recording medium such as a magnetic disk, etc., prepared by using the magnetic paint, can have a magnetic coating film having a substantially uniform film thickness of not more than 0.9 .mu.m and a surface roughness of not more than 0.05 .mu.m Ra before surface finishing.

Hard disk magnetic recording medium comprising magnetic powder and a

A coating type, magnetic disk is produced by applying a magnetic paint containing magnetic powders in a dispersed state to a non-magnetic substrate, thereby forming a magnetic recording film thereon, and applying surface waves to the magnetic recording film in an undried state. By applying the surface waves to the magnetic recording film, dispersibility and orientation of the magnetic powders are improved and a longitudinally oriented, coating type magnetic disk with distinguished electromagnetic properties, such as a high S/N ratio, etc. can be obtained.

Process for producing a rigid magnetic disk by longitudinally generating

A method for magnetic orientation of a magnetic recording medium using Meissner effect of a superconductor and a system therefor and a magnetic recording medium produced thereby. The magnetic particles of plate hexagonal barium ferrite in the magnetic coating are allowed to orient in the longitudinal direction thereof so that a magnetic recording medium having a magnetic orientation in such direction with the magnetic particles can be obtained.

Method for magnetic orientation of magnetic recording medium using

The present invention proposes a ratio of an applied field H.sub.s to a coercivity H.sub.c as a parameter which gives an influence to the write/read characteristics of a magnetic coated recording medium, especially, a reproduction output E.sub.o at a low recording density and a recording density D.sub.50 which provides an output of the half of E.sub.o. By selecting the ratio H.sub.s /H.sub.c to be not larger than 2.1, a magnetic coated recording medium having large values of E.sub.o and D.sub.50 or suited to a high density magnetic recording can be provided with good reproducibility.

Magnetic coated recording medium and method of manfacturing the same

Disclosed is a magnetic recording medium comprising a predetermined substrate having or not having a soft magnetic thin film provided thereon, a layer formed thereon for controlling the columnar crystal grain size in a thin magnetic film formed on the substrate, and the thin magnetic film provided on the columnar crystal grain size control layer. The above-mentioned columnar crystal grain size control layer is a film having a close-packed hexagonal lattice structure and made of one element selected from among Ru, Sc, Y, and Zn, or two or more elements selected from among Ru, Sc, Y, Zn, and Ti; or a film having a close-packed hexagonal lattice structure and made of Co or a Co-based alloy. The columnar crystal grain size control layer may consist of two layers, the under layer of which is made of one or more elements selected from among Si, Ge, and Sn.

Magnetic recording medium

Disclosed is a perpendicular magnetic recording medium wherein an underlayer made of a material containing Si and/or Ge as its principal ingredient is deposited on a substrate, and a perpendicular magnetic film made of a Co-based alloy is deposited on the underlayer. With the perpendicular magnetic recording medium, the perpendicular magnetic film has an enhanced degree of C-axis orientation, and the bond strength between the perpendicular magnetic film and the substrate is also enhanced when the substrate is non-metallic.

Perpendicular magnetic recording medium

A perpendicular magnetic recording medium free from spike noise having a high permeability magnetic material film, an antiferromagnetic material film and a perpendicularly oriented magnetic material film formed on a substrate in this order. Another high permeability magnetic material film may be formed between the antiferromagnetic material film and the perpendicularly oriented magnetic material film. During the formation of the antiferromagnetic material film, a magnetic field is applied in a direction of a track width.

Perpendicular magnetic recording medium and manufacturing method thereof

A magnetic recording medium comprising a substrate, an underlayer provided on the substrate and having a high permeability magnetic film and a relative permeability in all directions in the film surface of not less than 800, and a recording medium layer provided on the underlayer and having a perpendicular anisotropy. The recording and reproduction characteristics of this magnetic recording medium do not vary even when the direction of movement thereof with respect to a magnetic head varies. When it is applied to a magnetic disc, preferable results can be obtained.

In a perpendicular magnetic recording medium comprising a high permeability film and a perpendicular magnetization film which are laminated on a non-magnetic substrate, a perpendicular magnetic recording medium is provided wherein a permanent magnet film is further sandwiched between the non-magnetic substrate and the high permeability film, thereby eliminating a spike noise.

A variable inductor wherein two closed magnetic circuits each having a predetermined gap in one place are constructed of a movable magnetic core and a fixed magnetic core. When the movable magnetic core is moved, the opposite area between both the magnetic cores in one of the closed magnetic circuits increases, while the opposite area between both the magnetic cores in the other closed magnetic circuit decreases. Thus, the inductances of coils wound around parts of the respective closed magnetic circuits vary complementarily.

Variable inductor

A digital displacement sensor includes a plurality of zigzag coils provided with projecting or convex portions having different pitches and arranged on the surface of a flat plate. A magnetic head consisting of a magnetic body and a coil is wound around part of the magnetic body, the magnetic head being supported so as to be moved, while maintaining a given gap from the surface of the flat plate, whereby a digital signal corresponding to the displacement of the magnetic head is sensed by means of a plurality of zigzag coils.

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Kokubunji, Japan

Yasutaro Uesaka