Patent ID: 6395413
Filing Date: 2002-05-28
Classification: G11B

Abstract:
A perpendicular magnetic recording medium comprising, at least, a perpendicular magnetic recording layer having a hexagonal closest packing (hcp) structure of which c-axis is perpendicular to a surface of the perpendicular magnetic recording layer, on a non-magnetic base, wherein the perpendicular magnetic recording layer has a saturation magnetization Ms of not more than 400 emu/cc, and a lattice constant c of the hexagonal closest packing structure is not more than 4.07 Ã¥, such that the coercivity Hc of the recording medium is not less than 2500 Oe and the squareness ratio Rs is not less than 0.6; andwherein the magnetic recording layer comprises: a 4-element system alloy of Coâ€”Crâ€”Nbâ€”Ta, and when composition ratios of Nb and Ta are made to be x (at %) and y (at %), respectively, the 4-element system alloy satisfies inequalities (1) and (2) as follows: x+y&gE;2â€ƒâ€ƒ(1) 3x/4+y&lE;3â€ƒâ€ƒ(2) andwherein x and y are each above zero.