2017 年 41 巻 6 号 p. 108-126
The review covers the research and development of perpendicular media nanostructure focusing on the recording layer. The recording layer material includes the Co-alloys with hcp structure, the magnetic multilayers, and the alloys with ordered structures that have high magneto-crystalline anisotropies (Ku). The technologies of underlayer or interlayer for aligning the easy magnetization axis of magnetic crystal grain perpendicular to the film plane are briefly reviewed including the high Ku magnetic materials for future recording media.
Observations of compositional and magnetization structures in sub-μm scale have played important roles in improving the recording layer. Typical data on these characteristics are explained in relation to the media structure improvements. Considering that high Ku magnetic materials will be employed in future recording media, basic experimental results related in controlling the easy magnetization axis and in keeping the surface flatness of L10-ordered magnetic materials are explained. Future possibilities for increasing the areal density beyond 1 Tb/in2 by improving the magnetic material and the nanostructure of recording layer are also discussed.