Magnetic recording medium with corrosion resistance and manufacturing method
View Patent ↗A magnetic recording medium with a granular magnetic recording layer excellent in corrosion resistance is provided. In one embodiment, after formation of, on a non-magnetic substrate, an NiTa adhesion layer, a soft magnetic layer, a Ta intermediate layer, an Ru intermediate layer, and a Co alloy granular magnetic recording layer, hydrogen (H 2 ) plasma processing is applied to the surface of the Co alloy granular magnetic recording layer. Then, a DLC protective film layer is formed and a lubricant layer is coated.
1. A magnetic recording medium comprising:
a non-magnetic substrate;
a soft magnetic layer formed over the non-magnetic substrate;
an intermediate layer formed on the soft magnetic layer;
a granular magnetic recording layer having a magnetic alloy separated by oxides, formed on the intermediate layer; and
a protective layer formed on the granular magnetic recording layer;
wherein a hydrogen concentration in the granular magnetic layer is higher than a hydrogen concentration in the soft magnetic layer and in the intermediate layer.
2. A magnetic recording medium according to claim 1 wherein the amount of hydrogen in the granular magnetic recording layer, when measured by a secondary ion mass spectrometry, is such that a ratio (H/Co) of 133Cs2+1H to 133Cs+59Co is about 2×10−3 or more.
3. A magnetic recording medium according to claim 1 wherein the granular magnetic recording layer comprises a Co alloy separated by Si oxides and formed into a columnar shape.
4. A magnetic recording medium according to claim 3 wherein the soft magnetic layer comprises a lower soft magnetic layer, an Ru layer and an upper soft magnetic layer.
5. A magnetic recording medium according to claim 4 wherein the lower and upper soft magnetic layers each contain Co, Ta, and Zr.
6. A magnetic recording medium according to claim 3 wherein the intermediate layer contains Ta and Ru.
7. A magnetic recording medium according to claim 1 wherein an adhesion layer is present between the non-magnetic substrate and the soft magnetic layer.
8. A magnetic recording medium according to claim 1 wherein a lubricant layer is present on the protective layer.
9. A magnetic recording medium according to claim 1 wherein a soft magnetic backing layer is present between the non-magnetic substrate and the soft magnetic layer.
10. A magnetic recording medium according to claim 1 , wherein the protective layer comprises diamond-like carbon.