Showa Denko Kabushiki Kaisha

Showa Denko K.k.

Hiroshi Ohsawa

Hiroyuki Watanabe

Hiroshi Sakai

Kenzo Hanawa

Kazunori Ohnami

Hiroshi Kanazawa

Hideo Yashima

Shin-ichi Ogawa

Daisuke Shiomi

Akira Fukizawa

The present invention relates to a magnetic recording medium, which has excellent magnetic characteristics. The present invention also relates to a method for producing a magnetic recording medium where a plurality of targets are repeatedly sputtered several times in sequential order to form non-magnetic and magnetic films on a substrate.

Magnetic recording medium and production process thereof

A magnetic recording medium comprising, in order, a non-metallic substrate; an amorphous metallic film having an amorphous structure; a crystal-structure-regulating film of NiP-based alloy; and a non-magnetic undercoat film and a magnetic film; and wherein the crystal-structure-regulating film has a film thickness of 50 nm or less, and a total film thickness of the amorphous metallic film and the crystal-structure-regulating film is at least 60 nm is disclosed.

Magnetic recording medium, production process thereof, magnetic recording and reproducing apparatus, and medium substrate

A magnetic recording medium having a substrate disc with microscopic bumps formed by focusing a laser beam, wherein spacings D between adjacent bumps in the circumferential direction of the disc are varied so that formula (1) is satisfied:

Magnetic recording medium and process for producing same

A laser beam is focused onto a substrate for texturing the substrate surface to form a multiplicity of microscopic bumps thereon, wherein the laser beam to be focused is continuously modulated at an I.sub.max /I.sub.min ratio in the range from 10 to 100 wherein I.sub.max is the maximum amplitude of pulse oscillating laser beam output and I.sub.min is the minimum amplitude of pulse oscillating laser beam output, while the minimum output of the laser beam is controlled to a level lower than the minimum energy required for creating the microscopic bumps. A magnetic recording medium having good CSS characteristics can be produced at a high production rate from the laser-textured substrate.

Process for producing magnetic recording medium

A magnetic recording medium having an improved CSS characteristics is made by a process including a surface texture treatment step of either (1) focusing an ultraviolet laser beam in a ring-shaped band, or (2) focusing a pulsed ultraviolet laser beam at an energy density of at least 0.01 J/cm.sup.2 but lower than the threshold level successively at least two times but up to 1,000 times, on a substrate composed of glass or silicon, followed by the formation of an undercoat, a magnetic layer, and a protective coating in this order on the surface-textured substrate.

Growing community of inventors

Ichihara, Japan

Hiroshi Ohsawa