Research Development Corporation of Japan

Other

The Research Institute for Electric and Magnetic Materials

Shigehiro Ohnuma

Tsuyoshi Masumoto

Yukio Nakanouchi

Takeshi Yano

Kiwamu Shirakawa

Nobukiyo Kobayashi

A thin-film magnetic field sensor is provided which includes two arms of a bridge circuit formed of a first element having a giant-magneto-resistant thin-film, and soft magnetic thin-films disposed one on either side thereof, with electrical terminals, and a second element having a giant-magneto-resistant thin-film, and conductive films disposed one on either side thereof, with electrical terminals. The electrical resistance value of the second element has sensitivity relative to the magnetic field, such that it is substantially zero when the magnetic field is small, but it changes equally to the first element due to causes other than the magnetic field. Since the output of the bridge circuit is in proportion to the difference in electrical resistance values between the first and second elements, part of a change due to causes other than the magnetic field is canceled in the output of the bridge circuit, whereby the magnetic field value can be accurately measured.

Thin-film magnetic field sensor

A perpendicular magnetic recording medium is formed of a substrate having 5.times.10.sup.5 -5.times.10.sup.9 fine projections per mm.sup.2 on the surface thereof, said projections having heights in the range of 0.01-10 .mu.m and diameters in the range of 0.01-1 .mu.m, and a ferromagnetic material deposited uniformly in a columnar form on the projections. The recording medium is produced by providing in advance fine projections, the heights and diameters of which are 0.01-10 .mu.m and 0.01-1 .mu.m respectively, on the surface of a substrate to a density of 5.times.10.sup.5 -5.times.10.sup.9 projections per mm.sup.2, and then causing a ferromagnetic material to deposit on the substrate from a vapor phase in such a way that the deposited material is preferentially allowed to adhere onto the projections and then to grow the ferromagnetic material in a direction perpendicular to the plane of the substrate. The present invention has expanded the ranges of usable substrate-forming materials and recording materials, i.e., ferromagnetic materials, and has also simplified the production process.

Perpendicular magnetic recording medium and production process thereof

A method of producing fine particles with a particle size of submicron or finer which comprises the steps of:

Method of producing fine particles

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Sendai, Japan

Shigehiro Ohnuma