Perpendicular magnetic recording medium

摘要

In a perpendicular magnetic recording medium having, over a substrate, a magnetic recording layer, an underlayer made of Ru or a Ru compound and provided below the magnetic recording layer, a pre-underlayer made of a nonmagnetic crystalline material, and a soft magnetic layer provided below the pre-underlayer, when the difference between the highest point and the lowest point of unevenness of the interface between the soft magnetic layer and the pre-underlayer, derived by a cross-sectional TEM image, is given as an interface roughness (nm) and the distance between the soft magnetic layer and the magnetic recording layer, excluding the soft magnetic layer and the magnetic recording layer, is given as a SUL-MAG distance (nm), interface roughness (nm)≦0.4 (nm) and interface roughness×SUL-MAG distance (nm)≦12 (nm) are satisfied.

主权项

1. A perpendicular magnetic recording medium comprising:
a substrate; over said substrate, a magnetic recording layer for recording a signal, an auxiliary recording layer provided above said magnetic recording layer and having a magnetic interaction with said magnetic recording layer, a separation layer comprising Ru or an Ru compound, a multi-layer underlayer comprising Ru or a Ru compound and provided below said magnetic recording layer, said underlayer having a first underlayer on a lower layer side and a second underlayer on an upper layer side just under the magnetic recording layer, grains of said second underlayer being coarser than grains of said first underlayer, a multi-layer pre-underlayer made of a nonmagnetic crystalline material for controlling a crystal orientation of said underlayer, and a soft magnetic layer provided below said pre-underlayer, wherein when a difference between a highest point and a lowest point of unevenness of an interface between said soft magnetic layer and said multi-layer pre-underlayer, derived by a cross-sectional TEM image, is given as an interface roughness (nm) and a distance between said soft magnetic layer and said magnetic recording layer, excluding said soft magnetic layer and said magnetic recording layer, is given as a SUL-MAG distance (nm), said interface roughness (nm)<0.4(nm) and said interface roughness (nm)×said SUL-MAG distance (nm)<12(nm) are satisfied, wherein said separation layer comprises WO3.