Disk drive with laminated magnetic thin films with sublayers for magnetic recording
View Patent ↗The invention includes a disk drive with a magnetic recording disk with an upper and lower sublayer in at least one magnetic layer of a laminated magnetic layer structure that includes a spacer layer that substantially decouples the magnetic layers. The lower sublayer has a lower boron content than the upper sublayer and a preferred embodiment is CoPtCrBTa. The upper sublayer is deposited onto the lower sublayer and is preferably CoPtCrB with a higher boron content than the lower sublayer. The composition of the lower sublayer gives it a very low moment with low intrinsic coercivity which would not be useful as a recording layer on its own. The upper sublayer is a higher moment alloy with high intrinsic coercivity. An embodiment of the invention includes a laminated magnetic layer structure which is antiferromagnetically coupled to a lower ferromagnetic layer.
1. A disk drive comprising:
a magnetic transducer including a read and a write head positionable to read and write magnetic transitions on a magnetic thin film disk; and
the magnetic thin film disk including:
first and second ferromagnetic layers separated by a spacer layer that substantially decouples the first and second magnetic layers with at least one of the first and second magnetic layers further comprising:
a first sublayer of ferromagnetic material of an alloy of CoCrPt including at least one element from the group consisting of boron and tantalum and having a composition of approximately 10-14 at. % Pt, 19-26 at. % Cr, 0-7 at. % boron, 0-3 at % Ta; and
a second sublayer of ferromagnetic material deposited on the first sublayer having a higher boron content than the first sublayer.
2. The disk drive of claim 1 wherein the second sublayer is CoPtCrB with a composition of 11-14 at. % Pt, 11-20 at % Cr, 8-16 at. % boron.
3. The disk drive of claim 1 wherein the first sublayer has a total atomic percentage of boron and tantalum combined of less than or equal to 7 atomic percent.
4. The disk drive of claim 1 wherein the first sublayer has a total atomic percentage of tantalum of less than or equal to 3 atomic percent.
5. The disk drive of claim 1 wherein the first or second layer of ferromagnetic material includes CoPtCrB.
6. The disk drive of claim 1 wherein the second sublayer is Co63Pt12Cr14B11.
7. The disk drive of claim 1 wherein the first sublayer is Co57Pt13Cr23B5Ta2.