Fujitsu Corporation

Nippon Telegraph and Telephone Public Corporation

Wakatake Matsuda

Seizi Hattori

Kazuo Kobayashi

Koichi Makino

Takehiko Nakagawa

Yoshikazu Ishii

Susumu Kawakami

Nobuo Inagaki

Akira Nohara

Akira Terada

A method of roducing .gamma.-Fe.sub.2 O.sub.3 magnetic disk medium of continuous thin film is provided, in which a deposition source is deposited on an opposed Al-alloy substrate by means of a reactive vacuum deposition technique and the deposited film is thermally treated so as to be the magnetic disk medium. As the deposition source, a ferroalloy containing about 1 to 10 at.% Ti and about 0.5 to 5 at.% Co is employed.

Method of producing magnetic thin film

A thin film of ferrite for use as a magnetic recording medium includes up to ten atomic percent of Nb based on the total number of metallic atoms in the ferrite film. This thin film of ferrite further includes up to fifteen atomic percent of Cu in addition to the Nb. The inclusion of Nb improves the squareness ratio and the coercive force of the recording medium, and also enlarges the temperature range of reduction from .alpha. -Fe.sub.2 O.sub.3 to one of the ferrites, i.e. Fe.sub.3 O.sub.4. The inclusion of Cu lowers the reduction temperature below 300.degree. C. According to the invention, a magnetic recording medium exhibiting excellent required properties, such as a high coercive force and a high squareness ratio, can be produced by a reliable process.

Magnetic recording medium and process for producing the same

A thin film of ferrite for use as a magnetic recording medium contain (a) Cu, (b) both Cu and Co, or (c) Cu, Co and Nb. The inclusion of Cu increases the temperature range for reduction from .alpha.-Fe.sub.2 O.sub.3 to one of the ferrites, i.e. Fe.sub.3 O.sub.4, and also lowers the above-mentioned reducting temperature. The addition of Co improves the magnetic properties of the ferrite. The simultaneous addition of Cu, Co and Nb provides .gamma.-Fe.sub.2 O.sub.3 with excellent magnetic properties, which are stable over wide temperature range for oxidizing the Fe.sub.3 O.sub.4 to the .gamma.-Fe.sub.2 O.sub.3.

Process for producing a magnetic recording medium

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Zama, Japan

Wakatake Matsuda