Laminated magnetic recording media with antiferromagnetically coupled layer as one of the individual magnetic layers in the laminate
First Claim
1. A magnetic recording medium comprising:
- a substrate;
a magnetic recording layer on the substrate and comprising an antiferromagnetically-coupled (AFC) layer, a ferromagnetic layer and a nonferromagnetic spacer layer separating the AFC layer and the ferromagnetic layer, the AFC layer comprising a first ferromagnetic film, a second ferromagnetic film and an antiferromagnetically coupling film located between the first and second ferromagnetic films and having a thickness and composition to provide antiferromagnetic exchange coupling of the first and second ferromagnetic films, the nonferromagnetic spacer layer being located between the second ferromagnetic film of the AFC layer and the ferromagnetic layer and having a thickness and composition wherein the ferromagnetic layer and the second ferromagnetic film of the AFC layer are not exchange coupled.
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Abstract
A laminated magnetic recording medium for data storage has an antiferromagnetically-coupled (AFC) layer and a single ferromagnetic layer spaced apart by a nonferromagnetic spacer layer. The AFC layer is formed as two ferromagnetic films antiferromagnetically coupled together across an antiferromagnetically coupling film that has a composition and thickness to induce antiferromagnetic coupling. In each of the two remanent magnetic states, the magnetic moments of the two antiferromagnetically-coupled films in the AFC layer are oriented antiparallel, and the magnetic moment of the single ferromagnetic layer and the greater-moment ferromagnetic film of the AFC layer are oriented parallel. The nonferromagnetic spacer layer between the AFC layer and the single ferromagnetic layer has a composition and thickness to prevent antiferromagnetic exchange coupling. The laminated medium has improved thermal stability and reduced intrinsic media noise.
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Citations
18 Claims
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1. A magnetic recording medium comprising:
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a substrate;
a magnetic recording layer on the substrate and comprising an antiferromagnetically-coupled (AFC) layer, a ferromagnetic layer and a nonferromagnetic spacer layer separating the AFC layer and the ferromagnetic layer, the AFC layer comprising a first ferromagnetic film, a second ferromagnetic film and an antiferromagnetically coupling film located between the first and second ferromagnetic films and having a thickness and composition to provide antiferromagnetic exchange coupling of the first and second ferromagnetic films, the nonferromagnetic spacer layer being located between the second ferromagnetic film of the AFC layer and the ferromagnetic layer and having a thickness and composition wherein the ferromagnetic layer and the second ferromagnetic film of the AFC layer are not exchange coupled. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 16, 17, 18)
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15. A laminated magnetic recording medium comprising:
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a substrate;
a magnetic recording layer on the substrate and comprising an antiferromagnetically-coupled (AFC) layer, a ferromagnetic layer having a magnetic moment per unit area, and a nonferromagnetic spacer layer separating the AFC layer and the ferromagnetic layer;
the AFC layer comprising a first ferromagnetic film, a nonferromagnetic spacer film on the first ferromagnetic film, and a second ferromagnetic film exchange coupled antiferromagnetically to the first ferromagnetic film across the spacer film, one of the first and second ferromagnetic films having a magnetic moment per unit area greater than the magnetic moment per unit area of the other ferromagnetic film;
the magnetic recording layer exhibiting a major hysteresis loop with two remanent magnetic states in the absence of an applied magnetic field, wherein the orientations of the moments of the first and second ferromagnetic films are antiparallel in each remanent state but the first ferromagnetic film'"'"'s moment orientation in one remanent state is antiparallel to its orientation in the other remanent state, and the orientations of the moments of the ferromagnetic layer and the greater-moment ferromagnetic film are parallel in both remanent states.
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Specification