Perpendicular magnetic recording medium and system having a magnetic recording layer with a perpendicular recording layer, a magnetic coupling layer, and a writing assist layer
View Patent ↗Embodiments of the present invention provide a perpendicular magnetic recording medium having a substrate, a magnetic recording layer and a protective layer. The magnetic recording layer includes a perpendicular recording layer, a magnetic coupling layer and a writing assist layer. The perpendicular recording layer is a Co alloy layer containing an oxide disposed between the magnetic coupling layer and the substrate. The magnetic coupling layer is a ferromagnetic layer disposed between the perpendicular recording layer and the writing assist layer. The writing assist layer is a ferromagnetic layer disposed between the magnetic coupling layer and the protective layer. The saturation magnetization of the magnetic coupling layer is lower than the saturation magnetization of the perpendicular recording layer or the writing assist layer. The thickness of the magnetic coupling layer is 1 nm or more and 3 nm or less.
1. A perpendicular magnetic recording medium comprising a substrate, a magnetic recording layer and a protective layer, wherein
the magnetic recording layer includes a perpendicular recording layer, a magnetic coupling layer and a writing assist layer;
the perpendicular recording layer is a Co alloy layer containing an oxide disposed between the magnetic coupling layer and the substrate;
the magnetic coupling layer is a ferromagnetic layer disposed between the perpendicular recording layer and the writing assist layer;
the writing assist layer is a ferromagnetic layer disposed between the magnetic coupling layer and the protective layer;
the saturation magnetization of the magnetic coupling layer is lower than the saturation magnetization of the perpendicular recording layer or the writing assist layer; and
the thickness of the magnetic coupling layer is 1 nm or more and 3 nm or less.
2. The perpendicular magnetic recording medium according to claim 1 , wherein the saturation magnetization of the magnetic coupling layer is 300 kA/m or lower.
3. The perpendicular magnetic recording medium according to claim 1 , wherein the magnetic coupling layer contains an oxide.
4. The perpendicular magnetic recording medium according to claim 3 , wherein the oxide contained in the magnetic coupling layer is one of silicon oxide, tantalum oxide or titanium oxide, or a mixture thereof.
5. The perpendicular magnetic recording medium according to claim 1 , wherein the concentration of the oxide contained in the writing assist layer is lower than the concentration of the oxide in the perpendicular recording layer, or the writing assist layer 4 does not contain the oxide.
6. The perpendicular magnetic recording medium according to claim 1 , wherein the product of the saturation magnetization and the thickness of the magnetic coupling layer is less than the product of the saturation magnetization and the thickness of the perpendicular recording layer, and less than the product of the saturation magnetization and the thickness of the writing assist layer.
7. The perpendicular magnetic recording medium according to claim 1 , wherein the perpendicular recording layer contains Co, Cr, Pt, and silicon oxide; the magnetic coupling layer contains Co and Cr; and the writing assist layer contains Co, Cr, Pt, and B.
8. The perpendicular magnetic recording medium according to claim 1 , further comprising:
a soft magnetic underlayer having a first soft magnetic film and a second soft magnetic film anti-ferromagnetically coupled to each other and an interlayer disposed therebetween; and
an intermediate layer disposed between the soft magnetic underlayer and the magnetic recording layer.
9. A perpendicular magnetic recording medium including a substrate, a magnetic recording layer, and a protective layer, wherein
the magnetic recording layer includes a perpendicular recording layer, a magnetic coupling layer, and a writing assist layer;
the perpendicular recording layer is a Co alloy layer containing an oxide;
the magnetic coupling layer is a ferromagnetic layer disposed between the perpendicular recording layer and the writing assist layer;
the writing assist layer is a ferromagnetic layer comprising a Co alloy containing at least Cr and Pt,
the magnetic coupling layer is an alloy comprising Co and Cr as a main ingredient with the Co content of 70 at % or more and 75 at % or less; and
the thickness of the magnetic coupling layer is 1 nm or more and 3 nm or less.
10. The perpendicular magnetic recording medium according to claim 9 , wherein the first element group is a group of elements comprising Pt, B, Mo, Ta, V, Nb, and Ru where the magnetic coupling layer contains at least one element selected from the first group in addition to Co and Cr, and the total for the content of at least one element is 10 at % or less.
11. The perpendicular magnetic recording medium according to claim 9 , wherein the magnetic coupling layer contains an oxide.
12. The perpendicular magnetic recording medium according to claim 9 , wherein the concentration of the oxide contained in the writing assist layer is lower than the concentration of the oxide in the perpendicular recording layer, or the writing assist layer does not contain the oxide.
13. The perpendicular magnetic recording medium according to claim 9 , wherein the perpendicular recording layer contains silicon oxide, Co, Pt, and Cr, and the writing assist layer contains Co, Cr, Pt, and B.
14. The perpendicular magnetic recording medium according to claim 9 , further including:
a soft magnetic underlayer containing a first soft magnetic film and a second soft magnetic film anti-ferromagnetically coupled with each other and an interlayer layer disposed therebetween; and
an intermediate layer disposed between the soft magnetic underlayer and the magnetic recording layer.
15. A hard disk drive comprising:
a magnetic head including a writing main pole, an auxiliary return pole, and a trailing shield; and
a perpendicular recording medium including a substrate, a magnetic recording layer and a protective, the magnetic recording layer having a perpendicular recording layer, a magnetic coupling layer and a writing assist layer, wherein
the perpendicular recording layer is a Co alloy layer containing an oxide;
the magnetic coupling layer is a ferromagnetic layer disposed between the perpendicular recording layer and the writing assist layer;
the writing assist layer is a ferromagnetic layer comprising a Co alloy containing at least Cr and Pt;
the saturation magnetization of the magnetic coupling layer is lower than the saturation magnetization of the perpendicular recording layer or the writing assist layer; and
the thickness of the magnetic coupling layer is 1 nm or more and 3 nm or less.
16. The hard disk drive according to claim 15 , wherein the perpendicular recording layer contains Co, Cr, Pt, and silicon oxide; the magnetic coupling layer contains Co and Cr; and the writing assist layer contains Co, Cr, Pt, and B.
17. The hard disk drive according to claim 15 , wherein the magnetic coupling layer contain an oxide.
18. The hard disk drive according to claim 15 , further comprising:
a soft magnetic underlayer containing a first soft magnetic film and a second soft magnetic film anti-ferromagnetically coupled with each other and an interlayer comprising Ru as a main ingredient disposed between them; and an intermediate layer disposed between the soft magnetic underlayer and the magnetic recording layer.
19. A hard disk drive comprising:
a magnetic head including a writing main pole, an auxiliary return pole, and a trailing shield; and
a perpendicular recording medium including a substrate, a magnetic recording layer and a protective, the magnetic recording layer having a perpendicular recording layer, a magnetic coupling layer and a writing assist layer, wherein
the perpendicular recording layer is a Co alloy layer containing an oxide disposed between the magnetic coupling layer and the substrate;
the magnetic coupling layer is a ferromagnetic layer disposed between the perpendicular recording layer and the writing assist layer;
the writing assist layer is a ferromagnetic layer disposed between the magnetic coupling layer and the protective layer;
the magnetic coupling layer is an alloy comprising Co and Cr as a main ingredient with the content of Co of about 70 at % or more and 75 at % or less; and
the thickness of the magnetic coupling layer is 1 nm or more and 3 nm or less.
20. The hard disk drive according to claim 19 wherein when the first element group is a group of elements comprising Pt, B, Mo, Ta, V, Nb, and Ru, the magnetic coupling layer contains at least one element selected from the first group in addition to Co and Cr, and the total of the content of at least one of the elements is 10 at % or less.
21. The hard disk drive according to claim 19 , wherein the perpendicular recording layer contains Co, Cr, Pt, and silicon oxide; the magnetic coupling layer contains Co and Cr; and the writing assist layer contains Co, Cr, Pt, and B.
22. The hard disk drive according to claim 19 , wherein the magnetic coupling layer contains an oxide.
23. The hard disk drive according to claim 19 , further comprising:
a soft magnetic underlayer containing a first soft magnetic film and a second soft magnetic film anti-ferromagnetically coupled with each other and an interlayer comprising Ru as a main ingredient disposed between them; and an intermediate layer disposed between the soft magnetic underlayer and the magnetic recording layer.