Magnetic recording media for longitudinal recording, process for producing the same and magnetic memory apparatus

• US 20010053458A1
• Filed: 07/03/2001
• Published: 12/20/2001
• Est. Priority Date: 08/10/1988
• Status: Active Grant

• Current Assignee: Hitachi Global Storage Technologies Japan Limited (Hitachi, Ltd.)
• Original Assignee: Hitachi, Ltd.
• Inventors: Ohno, Tomoyuki, Yahisa, Yotsuo, Matsuda, Yoshibumi, Shige, Noriyuki, Hishiyama, Sadao, Ohura, Masaki, Suzuki, Hiroyuki, Shiroishi, Yoshihiro, Shirakura, Takaaki, Takagi, Kazumasa, Tsumita, Norikazu
• Granted Patent: US 6,627,253 B2
• Time in Patent Office: Days
• US Class Current: 428/611
• CPC Class Codes: G11B 5/656 containing Co containing inorganic, non-oxide compounds of Si, N, P, B, H or C G11B5/657; containing oxygen G11B5/658
• CPC Class Codes: G11B 5/658 containing oxygen, e.g. molecular oxygen or magnetic oxide
• CPC Class Codes: G11B 5/7369 Two or more non-magnetic underlayers, e.g. seed layers or barrier layers
• CPC Class Codes: G11B 5/7373 Non-magnetic single underlayer comprising chromium
• CPC Class Codes: Y10T 428/12465 having magnetic properties, or preformed fiber orientation coordinate with shape

Abstract

A magnetic recording medium for longitudinal recording with a low media noise, a high S/N ratio and high reliabilities in corrosion resistance is disclosed. By making a magnetic layer from a Co-based alloy comprising 1 to 35 at. % of at least one element selected from the group consisting of Pt and Ir, 1 to 17 at. % of at least one element selected from the group consisting of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Ge and Si, except for Si, whose concentration is 1 to 40 at. %, and 0.1 to 10 at. % of oxygen, a magnetic recording medium for longitudinal recording having an inplane coercivity of 1,200 Oe or more and a coercive squares of not more than 0.85 is obtained.

A process for producing the magnetic recording medium for longitudinal medium and a magnetic memory apparatus using the magnetic recording medium for longitudinal recording are also disclosed.

Claims

1. A magnetic recording medium for longitudinal recording, which comprises a nonmagnetic substrate and a magnetic layer provided on the nonmagnetic substrate, the magnetic layer being composed mainly of an alloy comprising Co, a material X composed of at least one element selected from the first group consisting of Cr, Mo and W, a material Y′

composed of at least one element selected from the second group consisting of Ti, Zr, Hf, Ta, Nb, Ru and Rh, and a material Z composed of at least one element selected from the third group consisting of Al and Si.

2. A magnetic recording medium for longitudinal recording according to

claim 1

, where the composition of the magnetic layer is represented by the following general formula:

(Co_1-aX_a)_1-b-cY′

_bZ_c

wherein 0.03≦

a≦

0.20, 0.01≦

b≦

0.15 and 0.01≦

c≦

0.15.

3. A magnetic recording medium for longitudinal recording according to

claim 1

, wherein the magnetic layer contains 0.1 at. % to 15 at. % of oxygen.

4. A magnetic recording medium for longitudinal recording according to

claim 2

, wherein the magnetic layer contains 0.1 at. % to 15 at. % of oxygen.

5. A magnetic recording medium for longitudinal recording according to

claim 3

, wherein an intermediate layer comprising a material composed of at least one element selected from the group consisting of Cr, Mo and W is provided between the magnetic layer and the nonmagnetic substrate.

6. A magnetic recording medium for longitudinal recording according to

claim 4

, wherein an intermediate layer comprising a material composed of at least one element selected from the group consisting of Cr, Mo and W is provided between the magnetic layer and the nonmagnetic substrate.

7. A magnetic recording medium for longitudinal recording which comprises a nonmagnetic substrate and a magnetic layer provided on the nonmagnetic substrate, the magnetic layer being composed mainly of an alloy comprising Co, Pt, a material X composed of at least one element selected from the first group consisting of Ni, Cr, Mo and W, a material Y′

composed of at least one element selected from the second group consisting of Ti, Zr, Hf, Ta, Nb, Ru and Rh, and a material Z composed of at least one element selected from the third group consisting of Al and Si.

8. A magnetic recording medium for longitudinal recording according to

claim 7

, wherein the composition of the magnetic layer is represented by the following general formula:

(Co_1-aNi_a)_1-b-c-dY′

_bZ_cPt_d,

wherein 0.1≦

a≦

0.5, 0.01≦

b≦

0.15, 0.01≦

c≦

0.15 and 0.001≦

d≦

0.20.

9. A magnetic recording medium for longitudinal recording according to

claim 7

, wherein wherein B′

is a material composed of at least one element selected from the group consisting of Cr, Mo and W, the composition of the magnetic layer is represented by the following general formula;

(Co_1-a′

B′

_a′

)_1-b-c-dY′

_bZ_cPt_d,

wherein 0.03≦

a′

≦

0.20, 0.01≦

b≦

0.15, 0.01≦

c≦

0.15 and 0.001≦

d≦

0.20.

10. A magnetic recording medium for longitudinal recording according to

claim 7

, wherein when B′

is a material composed of at least one element selected from the group consisting of Cr, Mo and W, the composition of the magnetic layer is represented by the following general formula;

(Co_1-a-eNi_aB′

_e)_1-b-c-dY′

_bZ_cPt_d,

wherein 0.1≦

a≦

0.5, 0.01≦

e≦

0.15, 0.01≦

b≦

0.15, 0.001≦

c≦

0.15 and 0.01≦

d≦

0.20.

11. A magnetic recording medium for longitudinal recording according to

claim 7

, wherein the magnetic layer contains 0.1 at. % to 15 at. % of oxygen.

12. A magnetic recording medium for longitudinal recording according to

claim 8

,

9

or 10, wherein the magnetic layer contains 0.1 at. % to 15 at. % of oxygen.

13. A magnetic recording medium for longitudinal recording according to

claim 11

, wherein an intermediate layer comprising a material composed of at least one element selected from the group consisting of Cr, Mo and W is provided between the magnetic layer and the nonmagnetic substrate.

14. A magnetic recording medium for longitudinal recording according to

claim 12

, wherein an intermediate layer comprising a material composed of at least one element selected from the group consisting of Cr, Mo and W is provided between the magnetic layer and the nonmagnetic substrate.

15. A magnetic recording medium for longitudinal recording which comprises a nonmagnetic substrate, a nonmagnetic metallic underlayer composing at least one metal element selected from the group consisting of Cr, Mo, W, V, Nb and Ta, formed on the nonmagnetic substrate, and a magnetic layer of Co-based alloy, formed on the nonmagnetic metallic underlayer, the magnetic layer comprising 1 to 35 at. % of at least one first additive element selected from the group consisting of Pt and Ir, 1 to 17 at. % of at least one second additive element selected from the group consisting of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Ge and Si, except for Si, whose concentration is 1 to 40 at. %, and 0.1 to 10 at. % of oxygen, sum total of the first and second additive elements and the oxygen being 2.2 to 50 at. %.

16. A magnetic recording medium for longitudinal recording according to

claim 15

, wherein the second additve element comprises at least one element selected from the group A consisting of Cr, Mo, W, Ge and Si and at least one element selected from the group B consisting of Ti, Zr, Hf, V, Nb and Ta.

17. A magnetic recording medium for longitudinal recording according to

claim 15

, wherein the second additive element comprises at least one element selected from the group A consisting of Cr, Mo, W, Ge and Si.

18. A magnetic recording medium for longitudinal recording according to

claim 15

, wherein the nonmagnetic metallic underlayer comprises at least one metal element selected from the group consisting of Cr, Mo, W, V, Nb and Ta and at least one element selected from the group consisting of Ti, Si, Ge, Cu, Pt, Rh, Ru, Re, Pd and oxygen.

19. A magnetic recording medium for longitudinal recording according to

claim 15

, wherein the first additive element is Pt, and the second additive element is Cr and Si.

20. A magnetic recording medium for longitudinal recording according to

claim 18

, wherein the first additive element is Pt and the second additive element is Cr and Si.

21. A magnetic recording medium for longitudinal recording according to

claim 15

, wherein the magnetic layer of Co-based alloy has an inplane coercivity of at least 1,200 Oe and a coercive squareness S* of not more than 0.85.

22. A magnetic recording medium for longitudinal recording according to

claim 21

, wherein the nonmagnetic metallic underlayer has a thickness of 150 to 600 nm.

23. A process for producing a magnetic recording medium for longitudinal recording, which comprises a step of forming a nonmagnetic metallic underlayer comprising at least one metal element selected from the group consisting of Cr, Mo, W, V, Nb and Ta onto a nonmagnetic substrate by physical vapor deposition and a step of forming a magnetic layer of Co-based alloy comprising 1 to 35 at. % of at least one first additive element selected from the group consisting of Pt and Ir, 1 to 17 at. % of at least one second additive element selected from the group consisting of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Ge and Si, except for Si, whose concentration is 1 to 40 at. %, and 0.1 to 10 at. % of oxygen, sum total of the first and second additive elements and oxygen being 2.2 to 50 at. %, in an inert gas atmosphere containing a very small amount of oxygen by sputtering of a target containing the first and second additive elements.

24. A process according to

claim 23

, wherein the second additive element comprises a two-group system comprising at least one element selected from the group A consisting of Cr, Mo, W, Ge and Si and at least one element selected from the group B consisting of Ti, Zr, Hf, V, Nb and Ta.

25. A process according to

claim 23

, wherein the second additive element comprises at least one element selected from the group A consisting of Cr, Mo, W, Ge and Si.

26. A process according to

claim 23

, wherein a step of forming a nonmagnetic plating underlayer on the nonmagnetic substrate in advance to the step of forming the nonmagnetic metallic undelayer and a step of forming a carbon-containing protective layer after the step of forming the magnetic layer of Co-based alloy are further included.

27. A process according to

claim 26

, wherein the step of forming the nonmagnetic plating underlayer is a step of electroless plating of Ni—

P.

28. A magnetic memory apparatus, which comprises a magnetic recording medium, a driving means for turning the magnetic recording medium, a magnetic head, a head access means, and a read and write means for the magnetic head, the magnetic recording means being a magnetic recording medium for longitudinal recording, which comprises a nonmagnetic substrate and a magnetic layer provided on the nonmagnetic substrate, the magnetic layer being composed mainly of an alloy comprising Co, a material X composed of at least one element selected from the first group consisting of Cr, Mo and W, a material Y′

composed of at least one element selected from the second group consisting of Ti, Zr, Hf, Ta, Nb, Ru and Rh, and a material Z composed of at least one element selected from the third group consisting of Al and Si.

29. A magnetic memory apparatus according to

claim 28

, where the composition of the magnetic layer is represented by the following general formula:

(Co_1-aX_a)_1-b-cY′

_bZ_c

wherein 0.03≦

a≦

0.20, 0.01≦

b≦

0.15 and 0.01≦

c≦

0.15.

30. A magnetic memory apparatus according to

claim 28

, wherein the magnetic layer contains 0.1 at. % to 15 at. % of oxygen.

31. A magnetic memory apparatus according to

claim 29

, wherein the magnetic layer contains 0.1 at. % to 15 at. % of oxygen.

32. A magnetic memory apparatus according to

claim 30

, wherein an intermediate layer comprising a material composed of at least one element selected from the group consisting of Cr, Mo and W is provided between the magnetic layer and the nonmagnetic substrate.

33. A magnetic memory apparatus according to

claim 31

, wherein an intermediate layer comprising a material composed of at least one element selected from the group consisting of Cr, Mo and W is provided between the magnetic layer and the nonmagnetic substrate.

34. A magnetic memory apparatus according to

claim 28

, wherein the magnetic recording medium is a magnetic recording medium for longitudinal recording which comprises a nonmagnetic substrate and a magnetic layer provided on the nonmagnetic substrate, the magnetic layer being composed mainly of an alloy comprising Co, Pt, a material X composed of at least one element selected from the first group consisting of Ni, Cr, Mo and W, a material Y′

composed of at least one element selected from the second group consisting of Ti, Zr, Hf, Ta, Nb, Ru and Rh, and a material Z composed of at least one element selected from the third group consisting of Al and Si.

35. A magnetic memory apparatus according to

claim 34

, wherein the composition of the magnetic layer is represented by the following general formula:

(Co_1-aNi_a)_1-b-c-dY′

_bZ_cPt_d,

wherein 0.1≦

a≦

0.5, 0.01≦

b≦

0.15, 0.01≦

c0.15 and 0.001≦

d≦

0.20.

36. A magnetic memory apparatus according to

claim 34

, wherein B′

is a material composed of at least one element selected from the group consisting of Cr, Mo and W, the composition of the magnetic layer is represented by the following general formula;

(Co_1-a′

B′

_a′

)_1-b-c-dY′

_bZ_cPt_d,

wherein 0.03≦

a′

≦

0.20, 0.01≦

b≦

0.15, 0.01≦

c≦

0.15 and 0.001≦

d≦

0.20.

37. A magnetic memory apparatus according to

claim 34

, wherein when B′

is a material composed of at least one element selected from the group consisting of Cr, Mo and W, the composition of the magnetic layer is represented by the following general formula;

(Co_1-a-eNi_aB′

_e)_1-b-c-dY′

_bZ_cPt_d,

wherein 0.1≦

a≦

0.5, 0.01≦

e≦

0.15, 0.01≦

b≦

0.15, 0.001≦

c≦

0.15 and 0.01≦

d≦

0.20.

38. A magnetic memory apparatus according to

claim 34

, wherein the magnetic layer contains 0.1 at. % to 15 at. % of oxygen.

39. A magnetic memory apparatus according to

claim 35

,

36

or 37, wherein the magnetic layer contains 0.1 at. % to 15 at. % of oxygen.

40. A magnetic memory apparatus according to

claim 38

, wherein an intermediate layer comprising a material composed of at least one element selected from the group consisting of Cr, Mo and W is provided between the magnetic layer and the nonmagnetic substrate.

41. A magnetic memory apparatus according to

claim 39

, wherein an intermediate layer comprising a material composed of at least one element selected from the group consisting of Cr, Mo and W is provided between the magnetic layer and the nonmagnetic substrate.

42. A magnetic memory apparatus according to

claim 28

, wherein the magnetic recording medium is a magnetic recording medium for longitudinal recording which comprises a nonmagnetic substrate, a nonmagnetic metallic underlayer comprising at least one metal element selected from the group consisting of Cr, Mo, W, V, Nb and Ta, formed on the nonmagnetic substrate, and a magnetic layer of Co-based alloy, formed on the nonmagnetic metallic underlayer, the magnetic layer comprising 1 to 35 at. % of at least once first additive element selected from the group consisting of Pt and Ir, 1 to 17 at. % of at least one second additive element selected from the group consisting of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Ge and Si, except for Si, whose concentration is 1 to 40 at. %, and 0.1 to 10 at. % of oxygen, sum total of the first and second additive elements and the oxygen being 2.2 to 50 at. %.

43. A magnetic memory apparatus according to

claim 42

, wherein the second additive element comprises at least one element selected from the group A consisting of Cr, Mo, W, Ge and Si and at least one element selected from the group B consisting of Ti, Zr, Hf, V, Nb and Ta.

44. A magnetic memory apparatus according to

claim 42

, wherein the second additive element comprises at least one element selected from the group A consisting of Cr, Mo, W, Ge and Si.

45. A magnetic memory apparatus according to claim 42, wherein the nonmagnetic metallic underlayer comprises at least one metal element selected from the group consisting of Cr, Mo, W, V, Nb and Ta and at least one element selected from the group consisting of Ti, Si, Ge, Cu, Pt, Rh, Ru, Re, Pd and oxygen.

46. A magnetic memory apparatus according to

claim 42

, wherein the first additive element is Pt, and the second additive element is Cr and Si.

47. A magnetic memory apparatus according to

claim 45

, wherein the first additive element is Pt and the second additive element is Cr and Si.

48. A magnetic memory apparatus according to

claim 42

, wherein the magnetic layer of Co-based alloy has an inplane coercivity of at least 1,200 Oe and a coercive squareness S* of not more than 0.85.

49. A magnetic memory apparatus according to

claim 48

, wherein the nonmagnetic metallic underlayer has a thickness of 150 to 600 nm.