Ru/FeCoB crystalline soft magnetic underlayers with high antsotropy field for CoPtCr-SiO_2 granular perpendicular magnetic recording media

摘要

Ru/FeCoB/Ru/CoPtCr-SiO_2 films were fabricated as perpendicular magnetic recording media with crystalline soft magnetic underlayer (SUL). Ru/FeCoB layers possessed high in-plane anisotropy field H_k of 400 Oe and a bcc-FeCo (110) orientation. Crystalline orientation of the FeCoB in the SUL affected on a crystallite growth of a Ru intermediate layer deposited on it and on crystallite orientation of the CoPtCr-SiO_2 film deposited on the Ru intermediate layer. Ru/CoPtCr-SiO_2 films without Ru/FeCoB SULs exhibited a random orientation of Ru crystallites and the in-plane magnetic anisotropy. On the other hand, Ru/CoPtCr-SiO_2 films deposited on the Ru/FeCoB SULs exhibited (001) preferential orientations of the CoPtCr as well as the Ru intermediate layer and possessed perpendicular magnetic anisotropy. It was confirmed that the improvement of a bcc-FeCo (110) orientation in the SUL was effective to the improvement of a hcp-Ru (001) orientation. At the media for an intermediate layer thickness of 5 nm, the similar magnetic properties as that of 30 nm were obtained. It indicated that the application of a crystalline SUL promoted the reduction in the intermediate layer thickness.