Patent ID: 6878459

Claim:
A magnetic recording medium comprising: a non-magnetic base material; a ferromagnetic metal layer of a CoCrPtB alloy formed on top of said non-magnetic base material; and a metal underlayer disposed between said base material and said ferromagnetic metal layer, wherein, a coercive force Hc is at least 2000 (Oe), an anisotropic magnetic field Hk grain is at least 10,000(Oe), and said metal underlayer incorporates an underfilm of either one of Cr and a Cr alloy comprising Mo and/or W, wherein a lattice misfit of said metal underlayer and said ferromagnetic metal layer, as determined by an equation (y−x)/(x/2+y/2)·100(%), in which x represents a length obtained by multiplying by square root of 2 a lattice constant of said metal underlayer and y represents a c axis length of a crystal lattice of said ferromagnetic metal layer, is a value from 0.5% to 2.5%, and an axial length ratio a/b of an interatomic distance a in a direction of a normal line to said ferromagnetic metal layer relative to an interatomic distance b in a direction within a plane of said ferromagnetic metal layer is within a range from 1.002 to 1.008.