Fujitsu Corporation

Showa Denko K.k.

Wataru Yamagishi

Hiroto Takeshita

Masato Sagawa

Koji Matsumoto

Antony Ajan

Ryoichi Mukai

Akihiro Inomata

Jun Taguchi

Atsushi Tanaka

Hitoshi Suzuki

Kazunori Yamanaka

Iwao Okamoto

Nobuo Kamehara

Hiroyoshi Kodama

Shigenori Aoki

Koichi Niwa

Takuya Uzumaki

Yasuo Bamba

Kaoru Hashimoto

Tsutomu Iikawa

The method for manufacturing a magnetic recording medium in a shape of a disk includes forming convex sections repeating on the upper surface of an intermediate layer in the radial direction of the disk, and each having an upper surface that repulses magnetic particles; and filling the magnetic particles into concave sections sandwiched by the convex sections in a self-assembling way to form a magnetic recording layer with the magnetic particles.

Manufacturing method for magnetic recording medium

A magnetic recording medium includes a first magnetic layer; and a second magnetic layer formed on the first magnetic layer. The first magnetic layer and the second magnetic layer make exchange coupling therebetween and also, have their magnetizing direction in anti-parallel to one another. A net residual area magnetization of the first magnetic layer and the second magnetic layer is expressed by the following formula: |Mr&#xd7;t&#x2212;Mr&#xd7;t| where Mrand Mrdenote respective residual magnetizations of the first magnetic layer and the second magnetic layer, and tand tdenote respective film thicknesses of them; and the net area magnetization at a first temperature is larger than the net area magnetization at a second temperature lower than the first temperature.

Magnetic recording medium, magnetic storage and method for reproducing information from magnetic recording medium

The surface of a disk medium includes a substrate whose surface includes grooves and lands. A non-magnetic underlayer and a magnetic recording layer are formed on the substrate. Smoothing non-magnetic film fills the grooves, which are covered with the non-magnetic underlayer and the magnetic recording layer, so that the height of the magnetic recording layer above the grooves may reach the same level as the height of the magnetic recording layer above the lands.

Magnetic memory medium having a magnetic film laminated on a substrate and a non-magnetic film formed thereon, and method of manufacturing the same

A magnetic hard disk having magnetic tracks for storing data which is read or written by a magnetic head floating immediately above the magnetic track while the magnetic hard disk is rotating, and the magnetic head rests on the magnetic hard disk while the magnetic hard disk is not rotating. One aspect of the present invention is that the magnetic hard disk comprises a non-magnetic substrate having a plurality of banks and grooves alternately and concentrically arranged thereon, a magnetic film formed on each of the banks, and non-magnetic material formed on an entire surface of the substrate all over the banks and grooves such that roughness of the upper surface of the non-magnetic material is in a range between 0.5 nm and 3 nm.

Method for manufacturing a magnetic hard disk having concentric magnetic tracks with flat surface

A magnetic hard disk has magnetic tracks for storing data, which is read or written by a magnetic head floating immediately above the magnetic track while the magnetic hard disk is rotating. The magnetic head rests on the magnetic hard disk while the magnetic hard disk is not rotating. The magnetic hard disk comprises a non-magnetic substrate having a plurality of banks and grooves alternately and concentrically arranged thereon, a magnetic film formed on each of the banks, and a non-magnetic material formed on an entire surface of the substrate all over the banks and grooves such that roughness of the upper surface of the non-magnetic material is in a range between 0.5 nm and 3 nm.

Magnetic hard disk having concentric magnetic tracks with flat surface and fabrication method thereof

A testing method for a magnetic recording medium which is magnetized measures variation of magnetization with the passage of time and evaluates the magnetic recording medium over its life. The method includes the steps of recording a first pattern at a density to be guaranteed in the magnetic recording medium, the first pattern having a difference between the sum total of areas of +bits and the sum total of areas of -bits, measuring remanence of the first pattern with the passage of time, and evaluating the magnetic recording medium over its life based on a measurement result.

Measurement method of time dependent magnetic remanence in a recording

A method of producing multi-layered ceramic circuit boards comprising laminated, component ceramic layers containing at least one hollow inorganic powder and at least one non-hollow inorganic powder. Signal transmitting conductor patterns of the boards are free from an irregular cross-sectional profile which is caused by particles of the hollow inorganic powder contained in the component ceramic layers. These multi-layered ceramic circuit boards are particularly useful for high speed transmission of digital signals of particularly high frequency.

Method of producing a multi-layered ceramic circuit board

A process of producing a multiple-layer glass-ceramic circuit board having a copper conductor, comprising the steps of: forming throughholes in a glass-ceramic green sheet at sites where via-contacts will be formed; filling the throughholes with a powder mixture of a copper powder blended with a ceramic powder, the copper powder and the ceramic powder having a powder particle size providing a packing density comparable with or greater than that of the glass-ceramic green sheet when filled in the throughholes; printing a conductor paste on the green sheet having the throughholes filled with the powder mixture, to form a circuit conductor pattern on the green sheet; laminating a plurality of the green sheets having the conductor pattern formed thereon, to form a laminate body; heating the laminate body to thereby remove a binder therefrom and preliminary-fire the laminate body; and firing the preliminary-fired body.

Process of producing multiple-layer glass-ceramic circuit board

The iron-cobalt type soft magnetic material contains 35% to 60% by weight of cobalt, 0.03% to 2.0% by weight of aluminum, the remainder being iron, and is prepared by powder metallurgy.

Iron-cobalt type soft magnetic material

Ferromagnetic material for temperature sensitive elements or parts has a direction of easy magnetization which varies depending upon temperature. The material has the formula:

Material for temperature sensitive elements

A temperature sensitive element comprises fine grain powders which consist of a spin reorientation type ferromagnetic material having a transition temperature range, below which transition temperature range the easy direction of magnetization of the spin reorientation type ferromagnetic material is predetermined in one crystallographic direction thereof and above which transition temperature range the easy direction of magnetization is a predetermined other direction perpendicular to the predetermined one crystallographic direction. The temperature sensitive element is produced by compacting the fine grain powders at a temperature higher than the transition temperature range. According to the present invention, it is possible to use a polycrystalline rare earth cobalt alloy material in the field where low Curie point ferrite has been used or where bimetals have been used for a thermal valve or a temperature controlling device.

Process and apparatus for producing a temperature sensitive element

A temperature sensitive element comprises fine grain powders which consist of a spin reorientation type ferromagnetic material having a transition temperature range, below which transition temperature range the easy direction of magnetization of the spin reorientation type ferromagnetic material is predetermined in one crystallographic direction thereof and above which transition temperature range the easy direction of magnetization is a predetermined other direction perpendicular to the predetermined one crystallographic direction. The temperature sensitive element is produced by compacting the fine grain powders of a spin reorientation type ferromagnetic material at a temperature higher than the transition temperature range. A polycrystalline rare earth cobalt alloy material made in accordance with the invention can now be used in the field where low Curie point ferrite or where bimetals have been used previously for a thermal valve or a temperature controlling device.

Growing community of inventors

Kawasaki, Japan

Wataru Yamagishi