Granted Patent B2

US 8,076,013 · App. 12/526,866 · Granted Dec 13, 2011

Abstract

Claims (28)

1. A magnetic recording medium comprising a substrate and a magnetic layer formed over the substrate, wherein:

the magnetic layer comprises a main recording layer for recording a magnetic signal and an auxiliary magnetic layer magnetically coupled to the main recording layer, and

the auxiliary magnetic layer comprises;

a plurality of hard magnetic portions respectively formed at positions corresponding to recording regions, where magnetic signals are to be recorded, in the main recording layer, and

magnetic field shield portions formed between but without being disposed over the plurality of hard magnetic portions, respectively, wherein when magnetization curves are measured, the magnetization curve of each magnetic field shield portion has a slope greater than those of the hard magnetic portions in a region where an applied magnetic field is zero, and a residual magnetic polarization of each magnetic field shield portion is smaller than those of the hard magnetic portions.

2. A magnetic recording medium according to claim 1 , wherein the magnetic field shield portions are soft magnetic.

3. A magnetic recording medium according to claim 2 , wherein the magnetic field shield portions have an axis of easy magnetization in an in-plane direction parallel to a main surface of the substrate.

4. A magnetic recording medium according to claim 1 , wherein:

the magnetic recording medium is a magnetic recording medium for perpendicular magnetic recording,

the hard magnetic portions of the auxiliary magnetic layer are magnetic regions that exhibit perpendicular magnetic anisotropy due to interface magnetic anisotropy, and

the magnetic field shield portions of the auxiliary magnetic layer are magnetic regions of which an interface state is different from that of the hard magnetic portions and which exhibit substantially no perpendicular magnetic anisotropy due to interface magnetic anisotropy.

5. A magnetic recording medium according to claim 1 , wherein:

the main recording layer is a layer with a granular structure in which a nonmagnetic substance is segregated at grain boundaries of magnetic grains, and

the hard magnetic portions of the auxiliary magnetic layer are each a multilayer film in which layers of a Co compound and Pd layers or Pt layers are alternately laminated.

6. A magnetic disk in which a magnetic recording layer with a granular structure in which nonmagnetic grain boundary portions are formed between magnetic grains continuously grown in a columnar shape and a magnetically coupling layer adjacent to the magnetic recording layer and magnetically continuous in an in-plane direction of a nonmagnetic substrate are stacked in this order over the substrate, the magnetic disk wherein:

at least the magnetically coupling layer out of the magnetically coupling layer and the magnetic recording layer comprises;

a plurality of hard magnetic portions respectively formed at positions corresponding to recording regions, where magnetic signals are to be recorded, in the magnetic recording layer, and

magnetic field shield portions formed between but without being disposed over the adjacent hard magnetic portions, respectively, wherein when magnetization curves are measured, the magnetization curve of each magnetic field shield portion has a slope greater than those of the hard magnetic portions in a region where an applied magnetic field is zero, and a residual magnetic polarization of each magnetic field shield portion is smaller than those of said hard magnetic portions.

7. A magnetic disk according to claim 6 , wherein the hard magnetic portions in the magnetically coupling layer are formed at the positions corresponding to the recording regions, where the magnetic signals are to be recorded, of the magnetic recording layer and the soft magnetic portions are formed in regions other than the positions.

8. A magnetic disk according to claim 6 , wherein the soft magnetic portions and the hard magnetic portions are formed in concentric circles with respect to a center of the disk-shaped substrate.

9. A magnetic disk according to claim 6 , wherein the magnetic recording layer and the magnetically coupling layer are in contact with each other.

10. A magnetic disk according to claim 6 , wherein the magnetically coupling layer contains at least CoCrPt.

11. A magnetic disk in which a magnetic recording layer with a granular structure in which nonmagnetic grain boundary portions are formed between magnetic grains continuously grown in a columnar shape and a magnetically coupling layer magnetically coupled to the magnetic grains in the magnetic recording layer are stacked in this order over a nonmagnetic disk-shaped substrate, the magnetic disk wherein:

at least the magnetically coupling layer out of the magnetically coupling layer and the magnetic recording layer comprises hard magnetic portions and soft magnetic portions alternately adjacent to each other in a radial direction of said substrate magnetic field, said soft magnetic portions being formed between but without being disposed over or under the plurality of hard magnetic portions.

12. A magnetic disk according to claim 11 , wherein the hard magnetic portions in the magnetically coupling layer are formed at positions corresponding to recording regions, where magnetic signals are to be recorded, of the magnetic recording layer and the soft magnetic portions are formed in regions other than the positions.

13. A magnetic disk according to claim 11 , wherein the soft magnetic portions and the hard magnetic portions are formed in concentric circles with respect to a center of the disk-shaped substrate.

14. A magnetic disk according to claim 11 , wherein the magnetic recording layer and the magnetically coupling layer are in contact with each other.

15. A magnetic disk according to claim 11 , wherein the magnetically coupling layer contains at least CoCrPt.

Assignments (8)