Magnetic recording medium and manufacturing method thereof

Abstract

A high-density magnetic recording medium uses a nonmetallic substrate, while still providing high in-plane magnetic anisotropy and remanent coercivity. Such a medium can be formed by depositing a seed layer on a textured surface of the nonmetallic substrate in a gas mixture containing oxygen or nitrogen and an inert gas, while controlling the oxygen concentration or nitrogen concentration, and subsequently exposing the surface of the seed layer to oxygen or nitrogen.

Description

BACKGROUND [0001] Conventionally, metal substrates of an aluminum alloy or the like have been widely used as substrates of magnetic recording media. These metal substrates are processed to form circular grooves on their surfaces, which grooves are referred to as a texture. The texturing on the substrate surface prevents the magnetic head from contacting the recording medium to prevent wear, which can happen when the magnetic head flies over the magnetic recording medium during seeking, and to orient the in-plane magnetization direction in the circumferential direction, which is the recording direction. High-density magnetic recording can be formed with an “anisotropic medium,” where magnetic anisotropy is formed in the medium plane (in-plane magnetic anisotropy). The output characteristics of the recording medium correspond to the product of the magnetic layer thickness and the remanent magnetization (hereinafter described as thickness remanent magnetization product (Mrt)). [0002] W...

AI Technical Summary

Benefits of technology

This approach results in magnetic recording media with enhanced in-plane magnetic anisotropy and remanent coercivity, enabling higher recording density with reduced medium noise and improved signal-to-noise ratio, maintaining thermal stability and playback output.

Problems solved by technology

On the other hand, a magnetic recording medium that uses a nonmetallic substrate, even if texturing is carried out on the surface of the nonmetallic substrate, it is difficult to form a magnetic layer having a sufficient in-plane magnetic anisotropy.

Obtaining a magnetic recording medium that uses a textured nonmetallic substrate is difficult as described above, but proposals to overcome the noted problem have been made.

If the magnetic recording density is increased with an in-plane magnetic recording medium, the area of the medium per recorded bit becomes smaller, and hence the playback output drops, and playback becomes difficult.

Although the playback problem can be improved by using a high-sensitivity head (which increases the playback output), the medium noise is amplified at the same time to make reading of recorded information difficult.

If medium noise is reduced by reducing the thickness of the magnetic layer and decreasing the crystal grain size of the magnetic layer, the remanent coercivity drops dramatically and the playback output drops dramatically, and also the thermal stability of the recording magnetization state becomes poor so that loss of recorded information becomes problematic.

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