Effects of very thin carbon seedlayer on formation of hcp phase for CoCrPtB/Co{sub}60Cr{sun}40 perpendicular magnetic recording media

摘要

This paper reports on significant improvement of magnetic properties for CoCrPtB/Co{sub}60Cr{sub}40 perpendicular recording media by utilizing very thin C seedlayer even with the thickness of less than 1 nm. This is caused by the following microstructural characteristic: 1) the C seedlayer heated to higher than 200 ℃, reacts with CoCr intermediate layer, and results in the formation of nanocrystalline layer with the thickness of about 6 nm; 2) Cr-deprived hcp grains with Cr segregation structure grow on the nanocrystalline layer without forming σ-phase grains in the intermediate layer, 3) CoCrPtB magnetic layer epitaxially grows on the intermediate layer without forming initial layer, which behaves as soft ferromagnetic layer and degrades magnetic properties of the media.