Ｃｏ／Ｐｔ人工格子垂直磁気記録媒体へのＢ添加効果とＮｉＡｌシード層効果

Abstract

The effect of boron doping on the magnetic and recording performance was examined in [Co (0.4 nm)/Pt (1 nm)]9 superlattice media, and ways of reducing media noise while maintaining a large perpendicular anisotropy Ku were discussed. The boron was doped only in the Co layer. The Ku was found to decrease as the boron content increased beyond 15 vol.%, while maintaining a large value of 5.7×106 erg/cm3 even at 30 vol.% in the Co layer. Moreover, the addition of boron was found to reduce the strength of intergranular exchange coupling, probably owing to the reduction of the exchange stiffness, resulting in an improvement of the signal-to-medium-noise ratio, SNmR. It was also shown that the use of an NiAl seed layer for Co/Pt superlattice media enhances grain segregation, resulting in an improvement of SNmR. However, no significant improvement in SNmR was achieved by the boron doping for [Co (0.4 nm)/Pt (1 nm)]9 media with an NiAl seed layer.