Method of manufacturing a perpendicular magnetic recording medium
View Patent ↗[PROBLEMS] To provide a process for producing a magnetic recording medium, which can simultaneously realize increased high recording density, high impact resistance, and prevention of corrosion, by providing an underlayer which, even when formed at a low gas pressure, can exhibit a high level of coercive force. [MEANS FOR SOLVING PROBLEMS] A process for producing a perpendicular magnetic recording medium, comprising the step of forming a nonmagnetic underlayer ( 18 ) having a granular structure, in which crystal particles are grown in a column form, on a substrate, and forming a magnetic recording layer ( 20 ) having a granular structure in which magnetic particles are grown in a column form. The process is characterized in that the underlayer ( 18 ) is any one of CoCr or CoCrX (wherein X is a nonmagnetic material), CoCr-oxide, and CoCrX-oxide, and the film forming gas pressure of the underlayer ( 18 ) is not more than 4 Pa.
1. A perpendicular magnetic recording medium comprising:
a substrate,
over a main surface of the substrate, a soft magnetic layer or layers;
over the soft magnetic layer, a first orientation control layer with a hcp structure and, over the first orientation control layer, a second orientation control layer with an amorphous structure,
over the second orientation control layer, an underlayer having a granular structure in which nonmagnetic crystal grains are grown in a columnar shape, and
over the underlayer, a magnetic recording layer having a granular structure in which magnetic grains are grown in a columnar shape,
wherein said first orientation control layer comprises Ti,
said second orientation layer is formed between the first orientation control layer and the under layer and functions as a lattice spacing adjusting layer for blocking lattice spacing chains between the first orientation control layer and the underlayer, and
said underlayer comprises one of CoCr or CoCrX (X is a nonmagnetic substance), CoCr-oxide, and CoCrX-oxide.
2. A perpendicular magnetic recording medium according to claim 1 , wherein said second orientation control layer has the amorphous structure containing at least one of C, Mo, Nb, Zr, B, and Ta.
3. A perpendicular magnetic recording medium according to claim 1 , wherein the content of said Cr in said underlayer is 35 at % or more and 55 at % or less.
4. A perpendicular magnetic recording medium according to claim 1 , wherein, when said underlayer is CoCr-oxide or CoCrX-oxide, said oxide contains at least one of SiO2, TiO2, and Cr2O3.
5. A perpendicular magnetic recording medium according to claim 4 , wherein, when said underlayer is CoCr-oxide or CoCrX-oxide, the content of said oxide is 6 mol % or less.
6. A perpendicular magnetic recording medium according to claim 1 , wherein said underlayer has a thickness of 15 nm or more.
7. A perpendicular magnetic recording medium according to claim 1 , wherein said second orientation control layer has a thickness of 0.5 nm or more and 1 nm or less.
8. A perpendicular magnetic recording medium according to claim 1 , wherein, when said underlayer is said CoCrX, said X contains at least one of B, Ru, Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, and W.
9. A perpendicular magnetic recording medium according to claim 1 , wherein an adhesive layer is between said substrate and said soft magnetic layer.