Magnetic recording medium, method for manufacturing magnetic recording medium and magnetic recording and reproducing apparatus

Patent metadata

Field	Value
Publication number	US-2018166100-A1
Application number	US-201715831579-A
Country	US
Kind code	A1
Filing date	Dec 5, 2017
Priority date	Dec 8, 2016
Publication date	Jun 14, 2018
Grant date	—

Abstract

A magnetic recording medium includes a non-magnetic substrate, a soft magnetic underlayer, an orientation control layer, a perpendicular magnetic layer, and a protective layer arranged in this order. The perpendicular magnetic layer includes a first magnetic layer and a second magnetic layer from the non-magnetic substrate side in this order. The second magnetic layer contains a magnetic grain and provided farthest from the non-magnetic substrate. The first magnetic layer has a granular structure that contains an oxide in a grain boundary. The second magnetic layer has a granular structure that contains a nitride of an element contained in the magnetic grain in a grain boundary.

First claim

What is claimed is

1 . A magnetic recording medium, comprising:
a non-magnetic substrate; a soft magnetic underlayer provided over the non-magnetic substrate; an orientation control layer provided over the soft magnetic underlayer; a perpendicular magnetic layer provided over the orientation control layer; a protective layer over the perpendicular magnetic layer; a first magnetic layer provided in the perpendicular magnetic layer and having a granular structure that contains an oxide in a grain boundary; and a second magnetic layer that contains a magnetic grain and is provided farthest from the non-magnetic substrate in the perpendicular magnetic layer, wherein the second magnetic layer has a granular structure that contains a nitride of an element contained in the magnetic grain in a grain boundary.

2 . The magnetic recording medium as claimed in claim 1 , wherein the element contained in the magnetic grain is boron, titanium, chrome, aluminum, tantalum, zirconium, or silicon.

3 . The magnetic recording medium as claimed in claim 1 , wherein the oxide is an oxide of silicon, chrome, titanium, aluminum, yttrium, boron, magnesium, tungsten, or cobalt.

4 . A method for manufacturing a magnetic recording medium including a non-magnetic substrate, a soft magnetic underlayer, an orientation control layer, a perpendicular magnetic layer, and a protective layer arranged in this order, the method comprising:
forming a first magnetic layer over the orientation control layer as part of the perpendicular magnetic layer by sputtering such that the first magnetic layer has a granular structure that contains an oxide in a grain boundary; forming a second magnetic layer having a non-magnetic structure and containing a magnetic grain at a location farthest from the orientation control layer in the perpendicular magnetic layer by sputtering; and nitriding part of an element contained in the magnetic grain such that a grain boundary is formed and thereby the second magnetic layer has a granular structure by performing a nitriding treatment on the second magnetic layer having the non-magnetic structure.

5 . The method as claimed in claim 4 , wherein the step of nitriding the part of the element comprises nitriding an element of boron, titanium, chrome, aluminum, tantalum, zirconium, or silicon.

6 . The method as claimed in claim 4 , wherein the step of forming the first magnetic layer comprises forming the first magnetic layer that contains the oxide of silicon, chrome, titanium, tantalum, aluminum, yttrium, boron, magnesium, tungsten, and cobalt in the grain boundary.

7 . A magnetic recording and reproducing apparatus, comprising:
a recording medium including:
a non-magnetic substrate;
a soft magnetic underlayer provided over the non-magnetic substrate;
an orientation control layer provided over the soft magnetic underlayer;
a perpendicular magnetic layer provided over the orientation control layer;
a protective layer over the perpendicular magnetic layer;
a first magnetic layer provided in the perpendicular magnetic layer and having a granular structure that contains an oxide in a grain boundary; and
a second magnetic layer that contains a magnetic grain and is provided farthest from the non-magnetic substrate in the perpendicular magnetic layer,
wherein the second magnetic layer has a granular structure that contains a nitride of an element contained in the magnetic grain in a grain boundary; and
a magnetic head configured to record information in the recording medium and to reproduce the recorded information from the magnetic recording medium.

Assignees

• Showa Denko Kk

Inventors

• Hasegawa Kota
• Ohashi Haruhisa

Classifications

• G11B5/72

  Protective coatings, e.g. anti-static {or antifriction} · CPC title

• G11B5/851

  Coating a support with a magnetic layer by sputtering · CPC title

• G11B5/70626

  containing non-metallic substances · CPC title

• G11B5/84

  Processes or apparatus specially adapted for manufacturing record carriers · CPC title

• G11B5/70605

  metals or alloys · CPC title