Magnetic recording medium for heat-assisted recording device and manufacturing method thereof

Patent metadata

Field	Value
Publication number	US-9263075-B2
Application number	US-201213347695-A
Country	US
Kind code	B2
Filing date	Jan 10, 2012
Priority date	Feb 2, 2011
Publication date	Feb 16, 2016
Grant date	Feb 16, 2016

Abstract

Disclosed are a magnetic recording medium for a heat-assisted recording device, which has a high SNR at high density, and a manufacturing method thereof. The magnetic recording medium includes a non-magnetic substrate; a magnetic recording layer; a protective layer; and a liquid lubricating layer. The magnetic recording layer has a granular structure formed by magnetic portions and non-magnetic portions that surround the magnetic portions in which the non-magnetic portions between adjacent magnetic portions are recessed with respect to the magnetic portions. The non-magnetic portions have a volume percentage based on total volume of the granular structure ranging from 15 vol % to 30 vol % and include a carbon-based material. The magnetic recording medium has a surface having an arithmetic mean roughness Ra and an average length of roughness curve elements RSm such that Ra/RSm ranges from 0.05 to 0.15.

First claim

What is claimed is:

1. A magnetic recording medium for a heat-assisted recording device, comprising, in the order recited:
a non-magnetic substrate;
a magnetic recording layer;
a protective layer; and
a liquid lubricating layer,
wherein the magnetic recording layer has a granular structure formed by magnetic portions and non-magnetic portions that surround the magnetic portions in which the non-magnetic portions between adjacent magnetic portions are recessed with respect to the magnetic portions, the non-magnetic portions having a volume percentage based on total volume of the granular structure ranging from 15 vol % to 30 vol % and including a carbon-based material, and
wherein the magnetic recording medium has a surface having an arithmetic mean roughness Ra and an average length of roughness curve elements RSm such that Ra/RSm ranges from 0.05 to 0.15.

2. The magnetic recording medium according to claim 1 , wherein the carbon-based material is C.

3. The magnetic recording medium according to claim 2 , wherein the volume percentage ranges from 20 vol % to 30 vol %.

4. The magnetic recording medium according to claim 1 , wherein the carbon-based material is B 4 C.

5. The magnetic recording medium according to claim 1 , further comprising at least one layer selected from the group consisting of a soft magnetic underlayer, an interlayer, and a heat sink layer provided between the non-magnetic substrate and the magnetic recording layer.

6. A magnetic recording medium for a heat-assisted recording device, comprising, in the order recited:
a non-magnetic substrate;
a magnetic recording layer comprising, in the order recited, a lower magnetic recording layer, an exchange coupling control layer, and an upper magnetic recording layer;
a protective layer; and
a liquid lubricating layer,
wherein the lower magnetic recording layer and the upper magnetic recording layer each have a granular structure formed by magnetic portions and non-magnetic portions that surround the magnetic portions in which the non-magnetic portions between adjacent magnetic portions of the upper magnetic recording layer are recessed with respect to the magnetic portions of the upper magnetic recording layer, each respective non-magnetic portion having a volume percentage ranging from 15 vol % to 30 vol %, and at least one of the lower magnetic recording layer and the upper magnetic recording layer including a carbon-based material, and
wherein the magnetic recording medium has a surface having an arithmetic mean roughness Ra and an average length of roughness curve elements RSm such that Ra/RSm ranges from 0.05 to 0.15.

7. The magnetic recording medium according to claim 6 , wherein the carbon-based material is C.

8. The magnetic recording medium according to claim 7 , wherein the volume percentage ranges from 20 vol % to 30 vol %.

9. The magnetic recording medium according to claim 6 , wherein the carbon-based material is B 4 C.

10. The magnetic recording medium according to claim 6 , further comprising at least one layer selected from the group consisting of a soft magnetic underlayer, an interlayer, and a heat sink layer provided between the non-magnetic substrate and the magnetic recording layer.

11. A method for manufacturing a magnetic recording medium for a heat-assisted recording device, comprising the steps of:
providing a non-magnetic substrate;
forming a magnetic recording layer on the non-magnetic substrate, the magnetic recording layer having a granular structure formed by magnetic portions and non-magnetic portions that surrounds the magnetic portions in which the non-magnetic portions between adjacent magnetic portions are recessed with respect to the magnetic portions;
forming a protective layer on the magnetic recording layer; and
forming a liquid lubricating layer on the protective layer,
wherein the non-magnetic portions have a volume percentage based on total volume of the granular structure that ranges from 15 vol % to 30 vol %, and include a carbon-based material, and
wherein the magnetic recording medium has a surface having an arithmetic mean roughness Ra and an average length of roughness curve elements RSm such that Ra/RSm ranges from 0.05 to 0.15.

12. The method according to claim 11 , wherein the carbon-based material is C.

13. The method according to claim 12 , wherein the volume percentage ranges from 20 vol % to 30 vol %.

14. The method according to claim 11 , wherein the carbon-based material is B 4 C.

15. The method according to claim 11 , further comprising the step of forming at least one layer selected from the group consisting of a soft magnetic underlayer, an interlayer, and a heat sink layer provided between the non-magnetic substrate and the magnetic recording layer.

16. A method for manufacturing a magnetic recording medium for a heat-assisted recording device, comprising the steps of:
providing the non-magnetic substrate;
forming a lower magnetic recording layer on a non-magnetic substrate;
forming an exchange coupling control layer on the lower magnetic recording layer;
forming an upper magnetic recording layer on the exchange coupling control layer;
forming a protective layer on the upper magnetic recording layer; and
forming a liquid lubricating layer on the protective layer,
wherein the lower magnetic recording layer and the upper magnetic recording layer each have a granular structure formed by magnetic portions and non-magnetic portions that surround the magnetic portions in which the non-magnetic portions between adjacent magnetic portions of the upper magnetic recording layer are recessed with respect to the magnetic portions of the upper magnetic recording layer, each respective non-magnetic portion having a volume percentage ranging from 15 vol % to 30 vol %, and at least one of the lower magnetic recording layer and the upper magnetic recording layer includes a carbon-based material, and
wherein the magnetic recording medium has a surface having an arithmetic mean roughness Ra and an average length of roughness curve elements RSm such that Ra/RSm ranges from 0.05 to 0.15.

17. The method according to claim 16 , wherein the carbon-based material is C.

18. The method according to claim 17 , wherein the volume percentage ranges from 20 vol % to 30 vol %.

19. The method according to claim 16 , wherein the carbon-based material is B 4 C.

20. The method according to claim 16 , further comprising the step of forming at least one layer selected from the group consisting of a soft magnetic underlayer, an interlayer, and a heat sink layer provided between the non-magnetic substrate and the magnetic recording layer.

Assignees

• Uchida Shinji
• Fuji Electric Co Ltd

Inventors

• Uchida Shinji

Classifications

• Y10T29/49021

  Magnetic recording reproducing transducer [e.g., tape head, core, etc.] · CPC title

• G11B5/65 Primary

  characterised by its composition (G11B5/66 takes precedence) · CPC title

• G11B5/66

  the record carriers consisting of several layers · CPC title

• G11B5/72

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

• G11B5/7266

  comprising a lubricant over the inorganic carbon coating · CPC title