Magnetic recording media with high SNR and high thermal stability
View Patent ↗Magnetic recording media exhibiting high SNR and high thermal stability are produced by sputter depositing a magnetic alloy overlying a non-magnetic substrate, e.g., on an underlayer, heating to eliminate thermally unstable small grains thereby increasing the average grain size of the magnetic alloy layer but narrowing the grain size distribution, depositing a layer comprising a non-ferromagnetic element, and then heating to diffuse the non-ferromagnetic element into the grain boundaries of the heat treated magnetic alloy layer. Embodiments include heating to diffuse the non-ferromagnetic element leaving a layer comprising the non-ferromagnetic element, at a thickness up to about 3Å, on the magnetic alloy layer, with the amount of the non-ferromagnetic element diffused into the grain boundaries of the magnetic alloy layer gradually decreasing from the upper surface of the magnetic alloy layer toward the underlayer.
1. A magnetic recording medium comprising:
a non-magnetic substrate;
a magnetic alloy layer overlying the substrate, the magnetic alloy layer having an upper surface, a lower surface and grains separated by grain boundaries, the magnetic alloy layer comprising a non-ferromagnetic element diffused into the grain boundaries in an amount gradually decreasing from the upper surface toward the lower surface; and
a layer containing the non-ferromagnetic element, having a thickness up to about 3Å, on the upper surface of the magnetic alloy layer.
2. The magnetic recording medium according to claim 1 , wherein the non-ferromagnetic element is at least one element selected from the group consisting of chromium (Cr), manganese (Mn) and tantalum (Ta).
3. The magnetic recording medium according to claim 1 , wherein the magnetic alloy layer comprises cobalt and platinum.
4. The magnetic recording medium according to claim 1 , wherein the magnetic alloy layer has an average grain size of about 8 to about 10 nm.
5. A magnetic recording medium comprising:
a non-magnetic substrate;
a magnetic alloy layer overlying the substrate, the magnetic alloy layer having an upper surface, a lower surface and grains separated by grain boundaries, the magnetic alloy layer comprising a non-ferromagnetic element diffused into the grain boundaries in an amount gradually decreasing from the upper surface toward the lower surface; and
a layer containing the non-ferromagnetic element on the upper surface of the magnetic alloy layer, wherein the non-ferromagnetic element is at least one element selected from the group consisting of manganese (Mn) and tantalum (Ta).
6. The magnetic recording medium according to claim 1 , wherein the layer comprising the non-ferromagnetic element has a thickness of about 0.5 to about 3Å.
7. The magnetic recording medium according to claim 1 , wherein the magnetic alloy layer comprises up to about 25 at. % of the non-ferromagnetic element.
8. The magnetic recording medium according to claim 7 , wherein at least about 80% of the non-ferromagnetic element in the magnetic alloy layer is within the grain boundaries of the magnetic alloy layer.
9. The magnetic recording medium according to claim 1 , further comprising a protective overcoat over the magnetic alloy layer.