Magnetic recording medium, its production process and magnetic recording device

1. A magnetic recording medium comprising a nonmagnetic substrate having applied thereon a magnetic recording layer, in which said substrate has, on an upper surface thereof, in sequence, a crystal orientation-improving layer and a seed layer consisting of a material having a higher surface energy than that of the crystal orientation-improving layer, and said seed layer has a thickness of not more than 2 nm, when the thickness is determined assuming that the seed layer has a continuous thickness;

wherein said magnetic recording layer is constituted from a four-component metal alloy of cobalt, chromium, platinum and tantalum which is represented by the following formula:

Co bal. —Cr 14-22 Pt 4-10 —Ta x

in which

bal. means a balance amount, and

x is in the range of 1 to 5 at %.

2. A magnetic recording medium according to claim 1 , in which said nonmagnetic substrate is a substrate of an aluminum-based alloy or a glass substrate.

3. A magnetic recording medium according to claim 1 or 2 , in which said seed layer is an island-like film consisting of an islandwise distributed and deposited material having a higher surface energy than that of the crystal orientation-improving layer.

4. A magnetic recording medium comprising a nonmagnetic substrate having applied thereon a magnetic recording layer, in which said substrate has, on an upper surface thereof, in sequence, a crystal orientation-improving layer and a seed layer consisting of a material having a higher surface energy than that of the crystal orientation-improving layer, and said seed layer has a thickness of not more than 2 nm, when the thickness is determined assuming that the seed layer has a continuous thickness;

wherein said seed layer comprises rhenium.

5. A magnetic recording medium according to claim 1 or 2 , in which said crystal orientation-improving layer comprises NiP or CrP.

6. A magnetic recording medium according to claim 1 or 2 , which further comprises an underlayer consisting of a chromium-based alloy between the seed layer and the magnetic recording layer.

7. A magnetic recording medium comprising a nonmagnetic substrate having applied thereon a magnetic recording layer, in which said substrate has, on an upper surface thereof, in sequence, a crystal orientation-improving layer and a seed layer consisting of a material having a higher surface energy than that of the crystal orientation-improving layer, and said seed layer has a thickness of not more than 2 nm, when the thickness is determined assuming that the seed layer has a continuous thickness;

wherein said magnetic recording layer is constituted from a five-component metal alloy of cobalt, chromium, platinum, tantalum and niobium which is represented by the following formula:

Co bal. —Cr 14-22 —Pt 4-10 —Ta x —Nb y

in which

bal. means a balance amount, and

a sum of x and y (x+y) is in the range of 1 to 5 at %.

8. The magnetic recording medium according to claim 1 or 2 , which further comprises, applied over said magnetic recording layer, a protective layer consisting of carbon or diamondlike carbon.

9. A magnetic recording medium according to claim 1 or 2 , which is in the form of a disk.

10. A magnetic recording device comprises a recording head section for recording in a magnetic recording medium and a reproducing head section for reproducing information, in which the magnetic recording medium comprises a nonmagnetic substrate having applied thereon a magnetic recording layer, in which said substrate has on a upper surface thereof, in sequence, a crystal orientation-improving layer and a seed layer consisting of a material having a higher surface energy than that of the crystal orientation-improving layer, said seed layer having a thickness of not more than 2 nm, when the thickness is determined assuming that the seed layer has a continuous thickness; and

said recording head section is provided with a magnetoresistive head;

wherein said magnetic recording layer is constituted from a four-component metal alloy of cobalt, chromium, platinum and tantalum which is represented by the following formula:

Co bal. —Cr 14-22 —Pt 4-10 —Ta x

in which

bal. means a balance amount, and

x is in the range of 1 to 5 at %.

11. A magnetic recording device according to claim 10 , in which said nonmagnetic substrate is a substrate of an aluminum-based alloy or a glass substrate.

12. The magnetic recording device according to claim 10 or 11 ,in which said magnetoresistive head is a MR head, an AMR head or a GMR head.

13. A magnetic recording device comprises a recording head section for recording in a magnetic recording medium and a reproducing head section for reproducing information, in which the magnetic recording medium comprises a nonmagnetic substrate having applied thereon a magnetic recording layer, in which said substrate has on a upper surface thereof, in sequence, a crystal orientation-improving layer and a seed layer consisting of a material having a higher surface energy than that of the crystal orientation-improving layer, said seed layer having a thickness of not more than 2 nm, when the thickness is determined assuming that the seed layer has a continuous thickness; and

said recording head section is provided with a magnetoresistive head;

wherein said magnetic recording layer is constituted from a five-component metal alloy of cobalt, chromium, platinum, tantalum and niobium which is represented by the following formula:

Co bal. —Cr 14-22 —Pt 4-10 —Ta x —Ta x —Nb y

in which

bal. means a balance amount, and

a sum of x and y (x+y) is in the range of 1 to 5 at %.

14. A magnetic recording medium according to claim 7 , in which said nonmagnetic substrate is a substrate of an aluminum-based alloy or a glass substrate.

15. A magnetic recording medium according to claim 7 or 14 , in which said seed layer is an island-like film consisting of an islandwise distributed and deposited material having a higher surface energy than that of the crystal orientation-improving layer.

16. A magnetic recording medium according to claim 7 or 14 , in which said crystal orientation-improving layer comprises NiP or CrP.

17. A magnetic recording medium according to claim 7 or 14 , which further comprises an underlayer consisting of a chromium-based alloy between the seed layer and the magnetic recording layer.

18. The magnetic recording medium according to claim 7 or 14 , which further comprises, applied over said magnetic recording layer, a protective layer consisting of carbon or diamondlike carbon.

19. A magnetic recording medium according to claim 7 or 14 , which is in the form of a disk.