PERPENDICULAR MAGNETIC RECORDING MEDIUM

• US 20100233515A1
• Filed: 03/12/2010
• Published: 09/16/2010
• Est. Priority Date: 03/13/2009
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd., Seagate Technology International (Seagate Technology Holdings Plc)
• Original Assignee: Fuji Electric Device Technology Company Limited (Fuji Electric Systems Company Limited), Samsung Electronics Co. Ltd.
• Inventors: Lee, Hoo-san, Watanabe, Sadayuki, Kong, Sok-hyun, Takenoiri, Shunji
• Granted Patent: US 10,026,429 B2
• Time in Patent Office: Days
• US Class Current: 428/846
• 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
• CPC Class Codes: G11B 5/676 having magnetic layers separated by a nonmagnetic layer, e.g. antiferromagnetic layer, Cu layer or coupling layer
• CPC Class Codes: G11B 5/678 having three or more magnetic layers

Abstract

A perpendicular type of magnetic recording medium has a multi-layered recording structure made up of a plurality of ferro-magnetic layers and a non-magnetic layer interposed between the plurality of ferro-magnetic layers, and the perpendicular magnetic anisotropy energy of the lower ferro-magnetic layer is greater than the perpendicular magnetic anisotropy energy of the upper ferro-magnetic layer. Accordingly, the lower ferro-magnetic layer may be easily magnetically reversed by a magnetic field applied during a write operation. Thus, the perpendicular type of magnetic recording medium exhibits an enhanced thermal stability and write-ability.

Claims

1. A perpendicular magnetic recording medium comprising:

a substrate;

a section of soft magnetic material in the form of a layer disposed on the substrate; and

a recording section disposed on the substrate above the section of soft magnetic material, the recording section comprising a plurality of ferro-magnetic layers, and a non-magnetic layer interposed between respective ones of the plurality of ferro-magnetic layers.

2. The perpendicular magnetic recording medium of claim 1, wherein the plurality of ferro-magnetic layers are magnetically separated from each other by the non-magnetic layer interposed between the plurality of ferro-magnetic layers.

3. The perpendicular magnetic recording medium of claim 1, wherein the non-magnetic layer is a layer of Ru or alloy of Ru.

4. The perpendicular magnetic recording medium of claim 1, wherein the plurality of ferro-magnetic layers comprise a lower ferro-magnetic layer, an upper ferro-magnetic layer, and a middle ferro-magnetic layer interposed between the lower ferro-magnetic layer and the upper ferro-magnetic layer, and

wherein the perpendicular magnetic anisotropy energy of the lower ferro-magnetic layer is greater than the perpendicular magnetic anisotropy energy of the middle ferro-magnetic layer.

5. The perpendicular magnetic recording medium of claim 4, wherein the perpendicular magnetic anisotropy energy of the lower ferro-magnetic layer is between 5×

10⁶ erg/cc and 5×

10⁷ erg/cc.

6. The perpendicular magnetic recording medium of claim 4, wherein the lower ferro-magnetic layer and the middle ferro-magnetic layer each have a granular structure.

7. The perpendicular magnetic recording medium of claim 4, wherein the saturated magnetization of the upper ferro-magnetic layer is greater than the saturated magnetization of the middle ferro-magnetic layer.

8. The perpendicular magnetic recording medium of claim 4, wherein the upper ferro-magnetic layer is a film of contiguous magnetic grains.

9. The perpendicular magnetic recording medium of claim 4, wherein the non-magnetic layer is interposed between the lower ferro-magnetic layer and the middle ferro-magnetic layer.

10. The perpendicular magnetic recording medium of claim 4, wherein the non-magnetic layer is interposed between the middle ferro-magnetic layer and the upper ferro-magnetic layer.

11. The perpendicular magnetic recording medium of claim 1, further comprising an intermediate section, disposed on the substrate directly beneath the recording section, wherein the intermediate section is of material that affects the crystalline orientation of the recording section as it is formed on the intermediate section.

12. The perpendicular magnetic recording medium of claim 10, wherein the intermediate section consists of at least one layer of material selected from the group consisting of Ru, an Ru oxide, MgO, and Ni.

13. The perpendicular magnetic recording medium of claim 1, wherein the soft magnetic material section comprise at least one layer of material selected from the group consisting of a Co-based material having an amorphous structure, an Fe-based soft magnetic material and an Ni-based soft magnetic material.