Stock material or miscellaneous articles – All metal or with adjacent metals – Having magnetic properties – or preformed fiber orientation...
Reexamination Certificate
2000-05-30
2002-08-06
Resan, Stevan A. (Department: 1773)
Stock material or miscellaneous articles
All metal or with adjacent metals
Having magnetic properties, or preformed fiber orientation...
C428S650000, C428S668000, C428S690000, C204S192200
Reexamination Certificate
active
06428906
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates generally to magnetic recording media such as magnetic thin film recording disks, and more particularly the invention relates to a magnetic recording media structure comprising a plurality of sputtered layers for achieving recording properties perpendicular to the plane of the media
The magnetic disk drive as used for data storage in computer systems comprises one or more disks having thin film magnetic layers on opposing surfaces for the recording of magnetic data as bits along concentric tracks. Typically, as shown in
FIG. 1A
, the disk comprises a substrate
4
of nickel phosphorous (NiP) or ceramic glass on which a plurality of layers are formed by sputtering in a low pressure inert gas atmosphere. The layers include a non-magnetic seedlayer
6
, a non-magnetic underlayer
8
of either pure chromium (Cr) or a chrome alloy (CrX), covered by a magnetic layer
10
of a cobalt-(Co) based alloy. A protective layer
12
of sputtered carbon (C) is typically used on top of the magnetic layer and an organic lubricant
14
may be used on top of the protective layer.
The magnetic layer can be either longitudinally magnetized in the plane of the layer or perpendicularly magnetized perpendicular to the plane of the layer. For perpendicular recording, a magnetically soft layer
7
, for example, NiFe, is often added to provide an image effect for the writing process. To achieve optimal perpendicular recording properties, the Co alloy magnetic layer has its easy axis magnetization aligned perpendicular to the plane of the disk. To achieve this, an underlayer such as close packed hexagonal (hcp) Ti or TiCr can be deposited to promote the growth of a hcp Co alloy perpendicular to the plane.
The present invention is directed to achieving an improved perpendicular magnetized magnetic layer through use of a reduced number of sputtered underlayers.
SUMMARY OF THE INVENTION
In accordance with the invention, a magnetic recording medium such as a magnetic disk comprises a substrate, an underlayer supported by the substrate with the underlayer preferably having a L
1
0
lattice structure, and a magnetic layer comprising an alloy of cobalt deposited on the underlayer and having a magnetization which is perpendicular to the magnetic layer.
In a preferred embodiment of the invention, the underlayer is titanium aluminum (TiAl) and the substrate comprises nickel phosphorous (NiP) or ceramic glass. The magnetic layer comprises a cobalt alloy such as CoCrTaPt or CoCrPtB.
While a carbon overcoat and lubricant layer may be included in the recording medium structure, the need for a magnetic soft layer or a non-magnetic underlayer of chromium is obviated. In other embodiments, the L
1
0
structure can be provided by alloys of other elements, and a disordered fcc structure can be employed, rather than the L
1
0
lattice.
The invention and objects and features thereof will be more readily apparent from the following detailed description and appended claims when taken with the drawing.
REFERENCES:
patent: 4652499 (1987-03-01), Howard
patent: 5131995 (1992-07-01), Suenaga et al.
patent: 5693426 (1997-12-01), Lee et al.
patent: 5718811 (1998-02-01), Chen et al.
patent: 5989728 (1999-11-01), Coffey et al.
patent: 6068739 (2000-05-01), Suzuki et al.
patent: 6218028 (2001-04-01), Song et al.
patent: 6248416 (2001-06-01), Lambeth et al.
patent: 03-193851 (1991-08-01), None
patent: 11-213371 (1999-08-01), None
Document Titled Site Preferences of Substitutional Si, Nb, Mo, Ta, and W Solid Solutions in L10 TiAl (Mar. 18, 1998).*
JPO Abstract Translation of JP-11-213371-A (Clipped Image No. JP411213371A).*
Machine Assisted Translation of JP 11-213371-A.*
Document Titled “PAC study of annealed TiAl” (no date given).*
Document Titled The CuAl (L10) Structure (last modified Apr. 5, 2001).*
Lambeth, David N. et al., “Magnetic Media Performance: Control Methods for Crystalline Texture and Orientation”, submitted for Publication in MRS Proceedings MRS Sym L: Paper #L8.1, Apr. 11 15, 1998 (Jun. 1, 1998), 12 pp.
Derwent Translation of JP 03-193851A (Derwent document number 4031935851A).
Wong Bunsen Y.
Zhang Lan
Bernatz Kevin M
Maxtor Corporation
Resan Stevan A.
Sigmond David M.
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