| 摘要 |
PROBLEM TO BE SOLVED: To obtain a perpendicular magnetic recording medium wherein magnetization is not attenuated by an external magnetic field and which has a stable signal and is nearly free from noise even when recording and reproduction are repeated. SOLUTION: The perpendicular magnetic recording medium has at least a substrate, a Co alloy bias layer, a soft magnetic layer and a magnetic recording layer which are laminated. In the Co alloy bias layer, the direction of its residual magnetization is directed in one direction of its radial directions and tsoft is 40 nm-200 nm. The magnetic recording medium satisfies the formula Mssoft×(tsoft -40 nm)>Mssoft×40 nm+Msbias×tbias . (tbias , Msbias , tsoft and Mssoft denote the thickness of the Co alloy bias layer, its saturation magnetization, the thickness of the soft magnetic layer and its saturation magnetization, respectively). |
