Granted Patent B2

US 6,899,959 · App. 10/075,123 · Granted May 31, 2005

Abstract

Claims (105)

1. A magnetic recording medium comprising:

a magnetic disk containing recorded data;

a read-write head; and

a motor coupled to rotate said magnetic disk;

said magnetic disk comprising:

a substrate;

a lower magnetic layer structure formed over said substrate;

an intermediate layer comprising Ru;

an upper magnetic layer structure formed over the intermediate layer, said upper magnetic layer structure being antiferromagnetically coupled to the lower magnetic layer structure, wherein the relationship between the dynamic coercivity of the lower magnetic layer structure and the exchange field is such that after termination of application of a write magnetic field to the usable locations on the disk the portion of the lower magnetic layer structure at said locations achieve substantially their steady magnetization state within 15 milliseconds.

2. The magnetic disk of claim 1 wherein at least one of said upper and lower magnetic layer structures comprise a plurality of layers.

3. The magnetic disk of claim 1 wherein a lowest magnetic layer structure is formed above said substrate, a second intermediate layer comprising Ru is formed between said lowest magnetic layer structure and said lower magnetic layer structure, and said lowest magnetic layer structure is antiferromagnetically coupled to said lower magnetic layer structure.

4. Magnetic disk drive of claim 1 wherein the Ms of the lower magnetic layer structure is greater than 300 emu/cm 3 .

5. The magnetic disk drive of claim 1 further comprising an underlayer formed between the substrate and the lower magnetic layer structure.

6. Magnetic disk drive of claim 1 wherein said lower magnetic layer structure comprises a layer comprising mostly Co, between 5 and 20 at. % Cr, 0 to 6 at. % Ta, 0 to 10 at. % B and 0 to 10 at. % Pt.

7. Magnetic disk drive of claim 6 wherein said layer of said lower magnetic layer structure comprises between 0 and 10% X, where X is one or more elements other than Co, Cr, Ta, B or Pt.

8. Magnetic disk drive of claim 6 wherein said layer of said lower magnetic structure comprises between 0 and 10% X, where X comprises one or more of Nb, Ta, Cu, Mo, W, V, Si, C, Pd, Ru, Ir or Y.

9. Magnetic disk drive of claim 1 wherein the upper magnetic layer structure comprises a layer comprising mostly Co, between 10 and 30 at. % Cr, between 8 and 20 at. % Pt, and 0 to 20 at. % B.

10. Magnetic disk drive of claim 9 wherein said layer of said upper magnetic layer structure comprises between 0 and 10 at. % X, wherein X is one or more elements other than Co, Cr, Pt or B.

11. Magnetic disk drive of claim 10 wherein X comprises one or more elements selected from Nb, Ta, Cu, Mo, W, V, Si, C, Pd, Ru, Ir or Y.

12. A magnetic disk drive comprising:

a magnetic disk containing recorded data;

a read-write head; and

a motor coupled to rotate said magnetic disk;

said magnetic disk comprising:

a substrate;

a lower magnetic layer structure formed over the substrate;

an intermediate layer comprising Ru; and

an upper magnetic layer structure formed over the intermediate layer, said upper magnetic layer structure being antiferromagnetically coupled to the lower magnetic layer structure, wherein the relationship between the dynamic coercivity of the lower magnetic layer structure and the exchange field is such that after termination of application of a write magnetic field to the usable locations on the disk the portion of the lower magnetic layer structure at said locations achieve more than 90% of thier steady magnetization state within 15 milliseconds.

13. A magnetic disk drive comprising:

a magnetic disk containing recorded data;

a read-write head; and

a motor coupled to rotate said magnetic disk;

said magnetic disk comprising:

a substrate;

a lower magnetic layer structure formed over the substrate;

an intermediate layer comprising Ru; and

an upper magnetic layer structure formed over the intermediate layer, said upper magnetic layer structure being antiferromagnetically coupled to the lower magnetic layer structure, wherein the relationship between the dynamic coercivity of the lower magnetic layer structure and the exchange field is such that after termination of application of a write magnetic field to the usable locations on the disk the portion of the lower magnetic layer structure at said locations achieve more than 95% of thier steady magnetization state within 15 milliseconds.

14. Disk drive of claim 1 , 12 , or 13 wherein said disk longitudinally records data in the uppermost magnetic layer of said disk.

15. A magnetic recording medium comprising:

a substrate;

a lower magnetic layer structure formed over the substrate;

an intermediate layer comprising Ru; and

an upper magnetic layer structure formed over the intermediate layer, said upper magnetic layer structure being antiferromagnetically coupled to the lower magnetic layer structure, data being recorded in said magnetic layer structures, wherein the relationship between the dynamic coercivity of the lower magnetic layer structure and the exchange field is such that after termination of application of a write magnetic field to the usable locations on the disk the portion of the lower magnetic layer structure at said locations achieve substantially their steady magnetization state within 15 milliseconds.

16. Magnetic recording medium of claim 15 wherein

said lower magnetic layer structure has a Ku between 0 and 10 6 erg/cm 3 ; and

said upper magnetic layer structure has a Ku greater than 10 6 erg/cm 3 .

17. Magnetic recording medium of claim 16 wherein said lower magnetic layer structure has a Ku less than 0.5×10 6 erg/cm 3 .

18. The magnetic recording medium of claim 16 wherein at least one of said upper and lower magnetic layer structures comprise a plurality of layers.

19. The magnetic recording medium of claim 16 wherein a lowest magnetic layer structure is formed above said substrate, a second intermediate layer comprising Ru is formed between said lowest magnetic layer structure and said lower magnetic layer structure, and wherein said lowest magnetic layer structure is antiferromagnetically coupled to said lower magnetic layer structure.

20. A magnetic disk drive comprising the magnetic recording medium of claim 16 .

21. A magnetic recording medium comprising:

a substrate;

a lower magnetic layer structure formed over the substrate;

an intermediate layer comprising Ru; and

an upper magnetic layer structure formed over the intermediate layer, said upper magnetic layer structure being antiferromagnetically coupled to the lower magnetic layer structure, data being recorded in said magnetic layer structures, wherein the relationship between the dynamic coercivity of the lower magnetic layer structure and the exchange field is such that after termination of application of a write magnetic field to the usable locations on the disk the portion of the lower magnetic layer structure at said locations achieve more than 90% of their steady magnetization state within 15 milliseconds.

22. A magnetic recording medium comprising:

a substrate;

a lower magnetic layer structure formed over the substrate;

an intermediate layer comprising Ru; and

an upper magnetic layer structure formed over the intermediate layer, said upper magnetic layer structure being antiferromagnetically coupled to the lower magnetic layer structure, data being recorded in said magnetic layer structures, wherein the relationship between the dynamic coercivity of the lower magnetic layer structure and the exchange field is such that after termination of application of a write magnetic field to the usable locations on the disk a portion of the lower magnetic layer structure at said locations achieve more than 95% of their steady magnetization state within 15 milliseconds.

23. Recording medium of claim 15 , 21 or 22 wherein said medium longitudinally records data in the uppermost magnetic layer of said medium.

24. A magnetic recording medium comprising:

a lower magnetic layer structure;

an intermediate layer comprising Ru formed over the lower magnetic layer structure; and

an upper magnetic layer structure comprising one or more magnetic layers antiferromagnetically coupled to the lower magnetic layer structure and formed over said intermediate layer, the dynamic coercivity of the lower magnetic layer structure being greater than or equal to zero but less than the exchange field between the upper and lower magnetic layer structures so that the magnetization direction in the one or more magnetic layers making up said upper magnetic layer structure is in a direction that is opposite to the magnetization direction of the lower magnetic layer structure, said upper magnetic layer structure comprising a data recording layer, the relation ship between said exchange field and the dynamic coercivity of said lower magnetic layer structure being such that locations in said lower magnetic layer structure substantially achieve their steady state magnetization state within 15 milliseconds of the end of the application of a write magnetic field to said locations.

25. Magnetic recording medium of claim 24 wherein said dynamic coercivity of said lower magnetic layer structure is less than one half of the exchange field.

26. Magnetic recording medium of claim 24 wherein said dynamic coercivity is for a recording switching time between 1 and 10 ns.

27. The magnetic recording medium of claim 24 wherein at least one of said upper and lower magnetic layer structures comprise a plurality of layers.

28. The magnetic recording medium of claim 24 wherein a lowest magnetic layer structure is formed above said substrate, a second intermediate layer comprising Ru is formed between said lowest magnetic layer structure and said lower magnetic layer structure, and said lowest magnetic layer structure is antiferromagnetically coupled to said lower magnetic layer structure.

29. A magnetic disk drive comprising the magnetic recording medium of claim 24 .

30. Magnetic recording medium comprising:

a substrate;

a lower magnetic layer structure formed over said substrate;

an intermediate layer comprising Ru formed over said lower magnetic layer structure; and

an upper magnetic layer structure comprising one or more magnetic layers formed over said intermediate layer, said upper magnetic layer structure being antiferromagnetically coupled to said lower magnetic layer structure, the coercivity of said lower magnetic layer structure as measured in a switching time of 10 milliseconds being less than the exchange field between said upper and lower magnetic layer structures so that the magnetization direction in the one or more magnetic layers making up said upper magnetic layer structure is in a direction that is opposite to the magnetization direction of the lower magnetic layer structure, said upper magnetic layer structure comprising a data recording layer, the relationship between said exchange field and the dynamic coercivity of said lower magnetic layer structure being such that locations in said lower magnetic layer structure substantially achieve their steady state magnetization state within 15 milliseconds of the end of the application of a write magnetic field to said locations.

31. Magnetic recording medium of claim 30 wherein said coercivity of said lower magnetic layer structure as measured in a switching time of 10 milliseconds is less than one half of the exchange field between said upper and lower magnetic layer structures.

32. The magnetic recording medium of claim 30 wherein at least one of said upper and lower magnetic layer structures comprises a plurality of layers.

33. The magnetic recording medium of claim 30 wherein a lowest magnetic layer structure is formed above said substrate, a second intermediate layer comprising Ru is formed between said lowest magnetic layer structure and said lower magnetic layer structure.

34. A magnetic disk drive comprising the magnetic recording medium of claim 30 .

35. Magnetic recording medium comprising:

a substrate;

a lower magnetic structure formed over said substrate, said lower magnetic structure comprising a magnetically soft material with intergranular decoupling;

an intermediate layer comprising Ru formed directly over said magnetically soft material; and

an upper magnetic layer structure comprising one or more magnetic layers formed over said intermediate layer, said upper magnetic layer structure being antiferromagnetically coupled to said lower magnetic layer structure so that the magnetization direction in the one or more magnetic layers making up said upper magnetic layer structure is in a direction that is opposite to the magnetization direction of the lower magnetic layer structure, said upper magnetic layer structure comprising a data recording layer.

36. Magnetic recording medium of claim 35 wherein said lower magnetic layer structure comprises an alloy selected from the list consisting of permalloy, sendust, CoTaZr, FeTaC, NiFeNb, CoFe, NiCrFe, NiV, CuNi, FeRh and PtMn.

37. A method comprising:

rotating a magnetic disk, said magnetic disk comprising a substrate, a lower magnetic layer structure formed over the substrate, an intermediate layer comprising Ru, and an upper magnetic layer structure formed over the intermediate layer, said upper magnetic layer structure being antiferromagnetically coupled to the lower magnetic layer structure;

storing data in the disk by applying write magnetic fields to locations on said magnetic disk; and

terminating the application of said write magnetic fields to said locations, wherein the relationship between the dynamic coercivity of the lower magnetic layer structure and the exchange field is such that after termination of application of write magnetic fields to said locations on the disk the portions of the lower magnetic layer structure at said locations achieve substantially their steady magnetization state within 15 milliseconds.

38. A method comprising:

rotating a magnetic disk, said magnetic disk comprising a substrate, a lower magnetic layer structure formed over the substrate, an intermediate layer comprising Ru, and an upper magnetic layer structure formed over the intermediate layer, said upper magnetic layer structure being antiferromagnetically coupled to the lower magnetic layer structure;

storing data in the disk by applying write magnetic fields to locations on said magnetic disk; and

terminating the application of said write magnetic fields to said locations, wherein the relationship between the dynamic coercivity of the lower magnetic layer structure and the exchange field is such that after termination of application of write magnetic fields to said locations on the disk the portions of the lower magnetic layer structure at said locations achieve more than 90% of their steady magnetization state within 15 milliseconds.

39. Method of claim 38 wherein the relationship between the dynamic coercivity of the lower magnetic layer structure and the exchange field is such that after termination of application of write magnetic fields to said locations on the disk the portions of the lower magnetic layer structure at said locations achieve more than 95% of their steady magnetization state within 15 milliseconds.

40. Method of claim 37 , 38 or 39 wherein said disk longitudinally records data in the uppermost magnetic layer of said disk.

41. A method comprising:

providing a magnetic recording medium, said magnetic recording medium comprising a substrate, a lower magnetic layer structure formed over the substrate, an intermediate layer comprising Ru, an upper magnetic layer structure formed over the intermediate layer, said upper magnetic layer structure being antiferromagnetically coupled to the lower magnetic layer structure;

storing data in the medium by applying write magnetic fields to locations on said magnetic recording medium; and

terminating the application of said write magnetic fields to said locations, wherein the relationship between the dynamic coercivity of the lower magnetic layer structure and the exchange field is such that after termination of application of said write magnetic fields to said locations on the medium the portions of the lower magnetic layer structure at said locations achieve substantially their steady magnetization state within 15 milliseconds.

42. A method comprising:

providing a magnetic recording medium, said medium comprising a substrate, a lower magnetic layer structure formed over the substrate, an intermediate layer comprising Ru, and an upper magnetic layer structure formed over the intermediate layer, said upper magnetic layer structure being antiferromagnetically coupled to the lower magnetic layer structure;

storing data in the medium by applying write magnetic fields to locations on said magnetic recording medium; and

terminating the application of said write magnetic fields to said locations, wherein the relationship between the dynamic coercivity of the lower magnetic layer structure and the exchange field is such that after termination of application of said write magnetic fields to said locations on the medium the portions of the lower magnetic layer structure at said locations achieve more than 90% of their steady magnetization state within 15 milliseconds.

43. Method of claim 42 wherein the relationship between the dynamic coercivity of the lower magnetic layer structure and the exchange field is such that after termination of application of write magnetic fields to said locations on the medium the portions of the lower magnetic layer structure at said locations achieve more than 95% of their steady magnetization state within 15 milliseconds.

44. Method of claim 41 , 42 or 43 wherein said medium longitudinally records data in the uppermost magnetic layer of said medium.

Assignments (9)