Hoya Corporation

Hoya Magnetics Singapore Pte. Ltd.

Wd Media, LLC

Masaki Uemura

Teiichiro Umezawa

Hisao Kawai

Hirotaka Tanaka

Yoshiaki Sonobe

Kong Kim

A magnetic diskfor use in perpendicular magnetic recording, which includes an underlayer, a size-reduction promoting layer(nonmagnetic granular layer) of a granular structure, and a magnetic recording layerhaving a ferromagnetic layerof a granular structure. The size-reduction promoting layerhas an inorganic oxide matrix and nonmagnetic metal crystal grains and is disposed between the underlayerand the ferromagnetic layer, thereby reducing the size of magnetic crystal grains in the ferromagnetic layer

Perpendicular magnetic recording disk and manufacturing method thereof

In a magnetic recording medium including a glass substrate () having a principal surface on which at least a magnetic layer () is formed, the magnetic recording medium has a coercive force of 2500 oersted or more in a circumferential direction thereof. The principal surface of the glass substrate is provided with a texture having a predetermined surface roughness so that the magnetic layer is given circumferential magnetic anisotropy. The magnetic recording medium further includes a magnetic anisotropy inducing layer () formed between the glass substrate and the magnetic layer so that the magnetic recording medium has an oriented ratio (OR) of 1.1 or more. The oriented ratio (OR) is defined as a ratio of a magnetic characteristic in circumferential direction to another magnetic characteristic in the radial direction.

Magnetic recording medium

In a magnetic recording medium including a substrate () having a principal surface on which first and second magnetic layers (and) and a spacer layer () are at least formed, each of the first and the second magnetic layers being of a ferromagnetic material, the spacer layer being formed between the first and the second magnetic layers for inducing antiferromagnetic exchange interaction between the first and the second magnetic layers, the principal surface of the substrate is provided with concentric textures to have a predetermined surface roughness so that the spacer layer has a uniform thickness. The first magnetic layer is for controlling the antiferromagnetic exchange interaction.

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Tokyo, Japan

Masaki Uemura