Stock material or miscellaneous articles – Web or sheet containing structurally defined element or... – Physical dimension specified
Patent
1997-10-17
2000-11-28
Kiliman, Leszek
Stock material or miscellaneous articles
Web or sheet containing structurally defined element or...
Physical dimension specified
428336, 428694T, 428694TS, 428900, 427128, 427129, 427130, 427131, 2041922, G11B 566
Patent
active
061532975
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a magnetic recording medium and a method of manufacturing the magnetic recording medium. More particularly, the present invention relates to a high density magnetic recording medium which has a high coercive force and a high normalized coercive force and which is excellent in an S/N ratio and a method of manufacturing the high density magnetic recording medium. The magnetic recording medium of the present invention is preferably used in a hard disk, a floppy disk, a magnetic tape or the like.
BACKGROUND ART
The following technology has been known in respect of a conventional magnetic recording medium and a method of manufacturing thereof.
FIG. 10 is an outline views for explaining a hard disk as an example of a magnetic recording medium. In FIG. 10, FIG. 10(a) is a perspective view showing a total of a magnetic recording medium and FIG. 10(b) is a sectional view taken from a line A--A' of FIG. 10(a).
A substrate body 1 where a nonmagnetic (Ni(nickel)-P(phosphor)) layer 3 is provided on the surface of an Al(aluminum) substrate 2 is used. Further, on top of the substrate 1, a Cr (chromium) base layer 4, a ferromagnetic metal layer 5 and a protective layer 6 are laminated in this order.
The substrate body 1 is constructed in which the nonmagnetic (Ni--P) layer 3 is formed on the surface of the Al substrate 2 in a disk shape having a diameter of 89 mm (3.5 inch) and a thickness of 1.27 mm (50 mil) by a plating process or a sputtering process. Further, inscriptions (hereinafter, referred to as texture) in concentric shapes are provided on the surface of the nonmagnetic (Ni--P) layer 3 by mechanical polishing. Generally, the surface roughness, that is, the mean center line roughness Ra which is measured in the radial direction is 5 nm through 15 nm. Further, the Cr base layer 4 and the ferromagnetic metal layer 5 (generally, a magnetic film of Co (cobalt) alloy group), are formed on the surface of the substrate body 1 by a sputtering process and finally, the protective layer 6 comprising carbon or the like is provided by a sputtering process to protect the surface of the ferromagnetic metal layer 5. Typical thicknesses of the respective layers are, 5 .mu.m through 15 .mu.m for the nonmagnetic (Ni--P) layer 3, 50 nm through 150 nm for the Cr base metal layer 4, 30 nm through 100 nm for the ferromagnetic metal layer 5 and 20 nm through 50 nm for the protective layer 6.
The conventional magnetic recording medium having the above-described layer structure is fabricated under conditions of a back pressure at the order of 10.sup.-7 Torr of a film forming chamber before film formation by sputtering and an impurity concentration of 1 ppm or more of Ar (argon) gas used in the film formation.
It has been reported by Nakai et al. that according to the magnetic recording medium provided by the above-described fabrication process, especially in the case of the ferromagnetic metal layer 5 including Ta (tantalum) element (for example, CoCrTa alloy magnetic film), grain boundaries constructed of an amorphous structure are present among crystal grains forming the ferromagnetic metal layer and the grain boundaries comprise a nonmagnetic alloy composition (J. Nakai, E. Kusumoto, M. Kuwabara, T. Miyamoto, M. R. Visokay, K. Yoshikawa and K. Itayama, "Relation Between Microstructure of Grain Boundary and the Intergranular Exchange in CoCrTa Thin Film for Longitudinal Recording Media", IEEE Trans. Magn., vol. 30, No. 6, pp. 3969, 1994).
However, in the case of the ferromagnetic metal layer that does not include Ta element (for example, CoNiCr (chromium) or CoCrPt (platinum) alloy magnetic film), the above-described grain boundaries have not been confirmed.
Further, it has been described that when the ferromagnetic metal layer includes Ta element, the normalized coercive force (designated as Hc/Hkgrain) is provided with a value as large as 0.3 or more whereas it has a value smaller than 0.3 when the ferromagnetic metal layer does not include Ta element.
Further, International Applica
REFERENCES:
patent: 5587235 (1996-12-01), Suzuki
patent: 5658658 (1997-08-01), Chen
patent: 5678473 (1997-10-01), Murayama
patent: 5853847 (1998-12-01), Tokakashi
Kiliman Leszek
Knuth Randall J.
LandOfFree
Magnetic recording medium and method of manufacturing the same does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Magnetic recording medium and method of manufacturing the same, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Magnetic recording medium and method of manufacturing the same will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1722921