Patent ID: 8404370

Claim:
A perpendicular magnetic recording medium comprising: a substrate, at least a magnetic recording layer with a granular structure in which a nonmagnetic grain boundary is formed between magnetic grains continuously grown into a columnar shape, wherein said magnetic grains contain Co, Cr, and Pt, and said magnetic recording layer contains at least one oxide selected from a group A comprising SiO 2 , TiO 2 , and Cr 2 O 3 , at least one oxide selected from a group B consisting of oxides each having a larger Gibbs free energy ΔG than said group A, and at least one oxide selected from a group C consisting of oxides each having a smaller Gibbs free energy ΔG than said group B, and wherein said magnetic recording layer is made of CoCrPt—TiO 2 —SiO 2 —Co 3 O 4 —SiO.