Perpendicular magnetic recording disc

• US 8,828,566 B2
• Filed: 05/20/2011
• Issued: 09/09/2014
• Est. Priority Date: 05/21/2010
• Status: Active Grant

• Current Assignee: JP Morgan Chase Bank, N.A. (JP Morgan Chase & Co)
• Original Assignee: WD Media Limited (Western Digital Corporation)
• Inventors: Sato, Tokichiro, Kajiwara, Takenori
• Primary Examiner(s): Rickman, Holly
• Assistant Examiner(s): CHAU, LINDA N
• Application Number:
  US13/112,433
• Publication Number:
  US 20120129009A1
• Time in Patent Office: 1,208 Days
• Field of Search: None
• US Class Current: 428/827
• CPC Class Codes: G11B 5/66 the record carriers consisting of several layers
• CPC Class Codes: G11B 5/672 having different compositions in a plurality of magnetic layers, e.g. layer compositions having differing elemental components or differing proportions of elements

Abstract

[Problem] An object is to make a film thinner while keeping the function as an auxiliary recording layer and increase an SNR.

[Solution] A structure of the perpendicular magnetic disk 100 according to the present invention includes, on a base 110, a granular magnetic layer 160 and an auxiliary recording layer 180 disposed above the granular magnetic layer, the granular magnetic layer having a granular structure in which a non-magnetic substance having an oxide as a main component is segregated around magnetic particles having a CoCrPt alloy as a main ingredient growing in a columnar shape to form a grain boundary part, and the auxiliary recording layer having a CoCrPtRu alloy as a main component and further containing, as a accessory component, a metal forming passivity and not being an antiferromagnet.

Claims

1. A perpendicular magnetic disk comprising, on a base, a granular magnetic layer and an auxiliary recording layer disposed above the granular magnetic layer,

the granular magnetic layer having a granular structure in which a non-magnetic substance having an oxide as a main component is segregated around magnetic particles having a CoCrPt alloy as a main ingredient growing in a columnar shape to form a grain boundary part, and

the auxiliary recording layer having a CoCrPtRu alloy as a main component and further containing, as an accessory component, a metal forming passivity and not being an antiferromagnet,

wherein the accessory component is any one or more elements selected from the group of Al and Ti, and a content of the accessory component is equal to or larger than 1 atomic percent and equal to or smaller than 3 atomic percent, and

wherein the auxiliary recording layer has a thickness of 1.5 nm to 4.0 nm.

2. The perpendicular magnetic disk according to claim 1, wherein

the auxiliary recording layer has saturation magnetization Ms equal to or larger than 550 emu/cc and equal to or smaller than 750 emu/cc.

3. The perpendicular magnetic disk according to claim 1, wherein

the auxiliary recording layer has a content of Cr equal to or larger than 3 atomic percent and equal to or smaller than 8 atomic percent.

4. The perpendicular magnetic disk according to claim 1, wherein the auxiliary recording layer having the CoCrPtRu alloy as the main component further comprises an additive selected from the group consisting of B, Ta and Cu.

5. The perpendicular magnetic disk according to claim 1, wherein the CoCrPtRu alloy as the main component of the auxiliary recording layer is CoCrPtRuB.

6. The perpendicular magnetic disk according to claim 1, wherein the accessory component is Al.

7. A perpendicular magnetic disk comprising, on a base, a granular magnetic layer and an auxiliary recording layer disposed above the granular magnetic layer,

the granular magnetic layer having a granular structure in which a non-magnetic substance having an oxide as a main component is segregated around magnetic particles having a CoCrPt alloy as a main ingredient growing in a columnar shape to form a grain boundary part, and

the auxiliary recording layer having a CoCrPtRu alloy as a main component and further containing, as an accessory component, a metal forming passivity and not being an antiferromagnet,

wherein the accessory component is any one or more elements selected from the group of Al and Ti, and

wherein the auxiliary recording layer has a thickness of 1.5 nm to 4.0 nm, and the auxiliary recording layer satisfies 4.5 atomic percent≦

(a content of Cr+0.75*a content of the accessory component)≦

8.75 atomic percent.

8. The perpendicular magnetic disk according to claim 7, wherein

the auxiliary recording layer has saturation magnetization Ms equal to or larger than 550 emu/cc and equal to or smaller than 750 emu/cc.

9. The perpendicular magnetic disk according to claim 7, wherein the auxiliary recording layer having the CoCrPtRu alloy as the main component further comprises an additive selected from the group consisting of B, Ta and Cu.

10. The perpendicular magnetic disk according to claim 7, wherein the CoCrPtRu alloy as the main component of the auxiliary recording layer is CoCrPtRuB.

11. The perpendicular magnetic disk according to claim 7, wherein the accessory component is Al.