Magnetic layering for bit-patterned stack
View Patent ↗A perpendicular magnetic recording layer of a magnetic recording medium includes a plurality of bit-patterned magnetic islands, wherein each of the plurality of islands overlay a soft magnetic under-layer. Each of the magnetic islands includes a first magnetic sub-layer adjacent a second magnetic sub-layer, wherein the first sub-layer has a relatively high magnetic anisotropy that is greater than a magnetic anisotropy of the second sub-layer. The magnetic recording layer further includes a third sub-layer, which extends to connect each of the plurality of islands. The third sub-layer may have a magnetic anisotropy that is less than that of the second sub-layer of each of the magnetic islands and/or may serve as an interlayer, extending between the first sub-layer and the soft magnetic under-layer of the recording medium, and having a structure to help to produce the greater anisotropy first magnetic sub-layer.
1. A system comprising:
a non-magnetic substrate;
a soft magnetic under-layer overlaying the substrate with anti-ferromagnetically coupled magnetic sub-layers;
a perpendicular magnetic recording layer comprising a plurality of bit-patterned magnetic features, each of the magnetic features overlaying the soft magnetic under-layer and each feature comprising a first magnetic sub-layer adjacent a second magnetic sub-layer, the recording layer further comprising a continuous third magnetic sub-layer overlaying the magnetic features to connect each of the magnetic features; and
a non-magnetic material layer deposited between each of the magnetic features;
wherein the first sub-layer of each of the magnetic features of the perpendicular magnetic recording layer has a magnetic anisotropy that is preconfigured to be consistently greater than a magnetic anisotropy of the second sub-layer of each of the magnetic features, and
wherein the second sub-layer of each of the magnetic features is configured for perpendicular magnetic recording; and
wherein the magnetic anisotropy of the second sub-layer of each of the plurality of magnetic features varies across a thickness of the second sub-layer from a maximum to a minimum and the minimum magnetic anisotropy of the second sub-layer of each of the magnetic features is greater than a magnetic anisotropy of the continuous third sub-layer of the perpendicular magnetic recording layer, and wherein the first sub-layer of each of the magnetic features of the perpendicular magnetic recording layer overlays the corresponding second sub-layer of each of the magnetic features.
2. The system of claim 1 , wherein the continuous third sub-layer of the perpendicular magnetic recording layer extends between the magnetic features of the perpendicular magnetic recording layer and the non-magnetic material layer.
3. The system of claim 1 , wherein the continuous third sub-layer of the perpendicular magnetic recording layer overlays the first sub-layer of each of the magnetic features of the perpendicular magnetic recording layer.
4. The system of claim 1 , wherein the thickness-varying magnetic anisotropy of the second sub-layer of each of the magnetic features is at the maximum at least at an interface with the corresponding first sub-layer of each of the magnetic features.
5. The system of claim 1 , wherein the thickness-varying magnetic anisotropy of the second sub-layer of each of the magnetic features is at the minimum at least at an interface with the corresponding first sub-layer of each of the magnetic features.
6. The system of claim 1 , wherein the second sub-layer of each of the magnetic features of the perpendicular magnetic recording layer overlays the corresponding first sub-layer of each of the magnetic features.
7. The system of claim 3 , further comprising a continuous interlayer overlaying the soft magnetic under-layer extending to connect each of the magnetic features.
8. The system of claim 7 , wherein the continuous interlayer has a thickness between approximately 0.3 nm and 30 nm.
9. The system of claim 7 , wherein the continuous interlayer comprises at least one of a face-centered cubic Ni alloy, a hexagonal close-packed Co alloy, a hexagonal close-packed Ti alloy, a hexagonal close-packed Ru alloy, a face-centered cubic Cu, a face-centered cubic Ag, a face-centered cubic Pt, a face-centered cubic Au, or a face-centered cubic Pd.
10. The system of claim 7 , wherein the continuous interlayer comprises at least one of MgO, CoO, FeO, NiO, RuAl, or CrRu.