Perpendicular magnetic recording medium and manufacturing method of the same

Patent metadata

Field	Value
Publication number	US-2017194026-A1
Application number	US-201615060871-A
Country	US
Kind code	A1
Filing date	Mar 4, 2016
Priority date	Jan 4, 2016
Publication date	Jul 6, 2017
Grant date	—

Abstract

According to one embodiment, a perpendicular magnetic recording medium includes a substrate, an underlayer including projections arranged at an average interval of 3 to 20 nm, an amorphous magnetic recording layer having a plurality of columnar magnetic grains on the surface of the projections, each having a magnetization easy axis in a direction perpendicular to a surface of the underlayer. The underlayer is formed such that 0.5d≦r≦1.5d, where r is the radius of curvature of a vertical section of each projection and d is the average interval between the projections.

First claim

What is claimed is:

1 . A perpendicular magnetic recording medium comprising:
a substrate; an underlayer including a plurality of projections arranged on the substrate at an average interval of 3 to 20 nm; and an amorphous magnetic recording layer having a plurality of magnetic grains formed as a column on the surface of the projections, the magnetic grains each having a magnetization easy axis in a direction perpendicular to a surface of the underlayer, wherein the projections are represented by the following formula (1)
0.5≦ r≦ 1.5 d   (1)

where r is the radius of curvature of a vertical section of each projection and d is the average interval between the projections.

2 . The perpendicular magnetic recording medium of claim 1 , wherein the underlayer has a multilayered structure of a first underlayer including projections and a second underlayer including projections formed on the first underlayer.

3 . The perpendicular magnetic recording medium of claim 2 , wherein the second underlayer is amorphous.

4 . The perpendicular magnetic recording medium of claim 2 , wherein the second underlayer is an anti-oxidation layer.

5 . The perpendicular magnetic recording medium of claim 4 , wherein the anti-oxidation layer includes at least one element selected from a group consisting of titanium, tantalum, hafnium, niobium, and zirconium, and at least one element selected from a group consisting of chrome, iron, nickel, copper, molybdenum, rhodium, palladium, and iridium.

6 . The perpendicular magnetic recording medium of claim 4 , wherein the anti-oxidation layer has a thickness of 1 to 30 nm.

7 . The perpendicular magnetic recording medium of claim 1 , wherein the amorphous magnetic recording layer contains a rare-earth element-transition metal alloy.

8 . The perpendicular magnetic recording medium of claim 7 , wherein the rare-earth element-transition metal alloy contains any of samarium, gadolinium, terbium, and dysprosium as a rare-earth element.

9 . The magnetic recording medium of claim 7 , wherein the rare-earth element-transition metal alloy contains one of iron and cobalt as a transition metal.

10 . The perpendicular magnetic recording medium of claim 7 , wherein the rare-earth element-transition metal alloy contains a terbium-cobalt alloy.

11 . The perpendicular magnetic recording medium of claim 1 , wherein the amorphous magnetic recording layer contains an additive which is any one of platinum, gold, silver, indium, chrome, titanium, silicon, aluminum, and boron.

12 . The perpendicular magnetic recording medium of claim 11 , wherein an amount of the additive is 30% or less of an entire composition of the amorphous magnetic recording layer.

13 . The perpendicular magnetic recording medium of claim 1 , wherein the amorphous recording layer has a thickness of 3 to 30 nm.

14 . The perpendicular magnetic recording medium of claim 1 , further comprising a nonmagnetic protective layer, wherein the nonmagnetic protective layer protects a part or the entirety of sidewalls of the amorphous magnetic recording layer.

15 . The perpendicular magnetic recording medium of claim 14 , wherein the nonmagnetic protective layer includes one to five layers therein.

16 . The perpendicular magnetic recording medium of claim 14 , wherein the nonmagnetic protective layer has a thickness of 0.5 to 3 nm.

17 . The perpendicular magnetic recording medium of claim 14 , wherein a total thickness of the nonmagnetic protective layer is one third or less of a total thickness of the amorphous magnetic recording layer.

18 . The perpendicular magnetic recording medium of claim 14 , wherein the nonmagnetic protective layer is formed of any of or an alloy of Pt, Pd, Au, Cu, Cr, and Al.

19 . The perpendicular magnetic recording medium of claim 1 , wherein, in the proximity of a crossing point representing the coercivity, the gradient α of the magnetization curve of the amorphous magnetic recording layer is less than five, the gradient being given by the following formula (2)
α=4π dM/dH|H=Hc   (2)

where M is the magnetization, H is the magnetic field, and Hc is the coercivity.

20 . A manufacturing method of a perpendicular magnetic recording medium, the method comprising:
forming, on a substrate, an underlayer including projections; and depositing an amorphous magnetic recording layer on surfaces of the projection, wherein the forming the underlayer including projections comprises: forming a first underlayer on the substrate; applying a nanoparticle dispersion fluid on the first underlayer to form a nanoparticle monolayer; and etching the first underlayer through the nanopartcles, and wherein the projections included in the underlayer are represented by the following formula (1)
0.5 d≦r≦ 1.5 d   (1)

where r is the radius of curvature of a vertical section of each projection and d is the average interval between the projections.

21 . The manufacturing method of claim 20 , further comprising:
forming a second underlayer including projections in advance to the deposition of the amorphous magnetic recording layer; and forming a multilayered underlayer including the first underlayer and the second underlayer, wherein the projections included in the multilayered underlayer are represented by the following formula (1)
0.5 d≦r≦ 1.5 d   (1)

where r is the radius of curvature of a vertical section of each projection and d is the average interval between the projections.

22 . The manufacturing method of claim 21 , wherein the second underlayer is amorphous.

23 . The manufacturing method of claim 21 , wherein the second underlayer is an anti-oxidation layer.

24 . The manufacturing method of claim 23 , wherein the anti-oxidation layer includes at least one element selected from a group consisting of titanium, tantalum, hafnium, niobium, and zirconium, and at least one element selected from a group consisting of chrome, iron, nickel, copper, molybdenum, rhodium, palladium, and iridium.

25 . The manufacturing method of claim 23 , wherein the anti-oxidation layer has a thickness of 1 to 30 nm.

26 . The manufacturing method of claim 20 , wherein the amorphous magnetic recording layer contains a rare-earth element-transition metal alloy.

27 . The manufacturing method of claim 26 , wherein the rare-earth element-transition metal alloy contains any of samarium, gadolinium, terbium, and dysprosium as a rare-earth element.

28 . The manufacturing method of claim 26 , wherein the rare-earth element-transition metal alloy contains one of iron and cobalt as a transition metal.

29 . The manufacturing method of claim 26 , wherein the rare-earth element-transition metal alloy contains a terbium-cobalt alloy.

30 . The manufacturing method of claim 20 , wherein the amorphous magnetic recording layer contains an additive which is any one of platinum, gold, silver, indium, chrome, titanium, silicon, aluminum, and boron.

31 . The manufacturing method of claim 30 , wherein an amount of the additive is 30% or less of an entire composition of the amorphous magnetic recording layer.

32 . The manufacturing method of claim 20 , wherein the amorphous recording layer has a thickness of 3 to 30 nm.

33 . The manufacturing method of

Assignees

• Toshiba Kk

Inventors

• Kimura Kaori
• Oikawa Soichi
• Iwasaki Takeshi

Classifications

• G11B5/855 Primary

  Coating only part of a support with a magnetic layer · CPC title

• G11B5/84 Primary

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

• G11B5/667

  including a soft magnetic layer · CPC title