MAGNETIC RECORDING MEDIUM FOR PERPENDICULAR MAGNETIC RECORDING

Abstract

A perpendicular recording medium having a perpendicular magnetic recording layer and a magnetically soft underlayer structure disposed beneath the recording layer. The soft underlayer structure includes at least first and second soft magnetic layers having different magnetic permeabilities to create a magnetic permeability gradient in the soft underlayer structure. One or more of the soft magnetic layers can be anti-parallel coupled. The soft underlayer structure of the present invention having a magnetic permeability gradient advantageously leads to reduced adjacent track erasure (ATE) while maintaining good overwrite (OW) properties.

Description

DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a top plan view of a disk drive device.

FIG. 2 illustrates a cross-sectional view of a perpendicular recording medium according to an embodiment of the present invention.

FIG. 3 illustrates a cross-sectional view of a soft underlayer structure for a perpendicular recording medium according to an embodiment of the present invention.

FIG. 4 illustrates a cross-sectional view of a soft underlayer structure for a perpendicular recording medium according to an embodiment of the present invention.

FIG. 5 illustrates a cross-sectional view of a soft underlayer structure for a perpendicular recording medium according to an embodiment of the present invention.

FIG. 6 illustrates a cross-track profile illustrating adjacent track erasure for perpendicular recording media.

FIG. 7 illustrates adjacent track erasure of perpendicular recording media as a function of magnetic permeability thickness product.

FIG. 8 illustrates adjacent track erasure of perpendicular recording media as a function of magnetic permeability.

FIG. 9 illustrates overwrite of perpendicular recording media as a function of magnetic permeability thickness product.

FIG. 10 illustrates overwrite of perpendicular recording media as a function of magnetic permeability.

FIG. 11 illustrates adjacent track erasure and overwrite for perpendicular recording media.

Claims

1. A magnetic recording medium for perpendicular magnetic recording, comprising: a substrate;a soft underlayer structure disposed over said substrate, said underlayer structure comprising a first soft magnetic layer having a first magnetic permeability, and a second soft magnetic layer that is disposed over said first soft magnetic layer and having a second magnetic permeability, wherein said first magnetic permeability is different than said second magnetic permeability;an intermediate layer disposed over said underlayer structure; anda perpendicular magnetic recording layer disposed over said intermediate layer.

2. A magnetic recording medium as recited in claim 1, wherein said underlayer structure further comprises a non-magnetic spacer layer disposed between said first and second soft magnetic layers.

3. A magnetic recording medium as recited in claim 1, wherein said second magnetic permeability is less than said first magnetic permeability.

4. A magnetic recording medium as recited in claim 1, wherein said underlayer structure further comprises at least a third soft magnetic layer having a third magnetic permeability, wherein said third magnetic permeability is different than either of said first and second magnetic permeabilities.

5. A magnetic recording medium as recited in claim 1, wherein said second soft magnetic layer has a thickness that is from about 10% to about 60% of a total thickness of the underlayer structure.

6. A magnetic recording medium as recited in claim 1, wherein said second soft magnetic layer has a thickness that is from about 20% to about 40% of a total thickness of the underlayer structure.

7. A magnetic recording medium as recited in claim 1, wherein said soft underlayer structure has a total thickness of from about 40 nm to about 160 nm.

8. A magnetic recording medium as recited in claim 1, wherein said second soft magnetic layer has a thickness of not greater than about 40 nm.

9. A magnetic recording medium for perpendicular magnetic recording, comprising: a substrate;a soft underlayer structure disposed over said substrate, said underlayer structure comprising a first soft magnetic layer having a first magnetic permeability, a second soft magnetic layer that is disposed over said first soft magnetic layer and having a second magnetic permeability, and a third soft magnetic layer having a third magnetic permeability, said third soft magnetic layer being disposed between said first and second soft magnetic layers, wherein said third magnetic permeability is higher than at least one of said first and second magnetic permeabilities;an intermediate layer disposed over said underlayer structure; anda perpendicular magnetic recording layer disposed over said intermediate layer.

10. A magnetic recording medium as recited in claim 9, wherein said third magnetic permeability is greater than either of said first and second magnetic permeabilities.

11. A magnetic recording medium as recited in claim 9, wherein said soft underlayer structure has a total thickness of from about 40 nm to about 160 nm.

12. A magnetic recording medium as recited in claim 9, wherein said third soft magnetic layer is fabricated from a soft magnetic material selected from the group consisting of FeTaNb, FeZr, CoNiFe and CoFe.

13. A magnetic recording medium for perpendicular magnetic recording, comprising: a substrate;a soft underlayer structure disposed over said substrate, said underlayer structure comprising a first anti-parallel coupled soft magnetic layered unit having a first magnetic permeability, a second anti-parallel coupled soft magnetic layered unit that is disposed over said first anti-parallel coupled soft magnetic layered unit and having a second magnetic permeability, wherein said first magnetic permeability is different than said second magnetic permeability;an intermediate layer disposed over said underlayer structure; anda perpendicular magnetic recording layer disposed over said intermediate layer.

14. A magnetic recording medium as recited in claim 13, wherein said second magnetic permeability is lower than said first magnetic permeability.

15. A magnetic recording medium as recited in claim 13, wherein a thickness of said second anti-parallel coupled soft magnetic layered unit is less than a thickness of said first anti-parallel coupled soft magnetic layered unit.

16. A magnetic recording medium as recited in claim 13, wherein each of said first and second anti-parallel coupled soft magnetic layered units comprise two layers of a soft magnetic material and a non-magnetic Ru layer disposed between the layers of soft magnetic material.

17. A magnetic recording medium as recited in claim 16, wherein said soft magnetic material comprises CoZrTa.

18. A magnetic recording medium as recited in claim 13, further comprising a non-magnetic spacer layer disposed between said first and second anti-parallel coupled soft magnetic layered units.

19. A magnetic recording medium as recited in claim 18, wherein said non-magnetic spacer layer comprises Ta.