Abstract
The effects of Ti, Pt and Ti/Pt stacked intermediate layers were studied on the microstructure of Co-Cr-Nb-Pt double layer perpendicular magnetic recording media by transmission electron microscopy (TEM). The media without intermediate layer exhibited hcp (0001) texture formed by heteroepitaxy on the 20-40nm diameter fcc (111) columns of the permalloy back layer. The applied Ti intermediate layer was amorphised due to a chemical reaction with the permalloy. The subsequent Co-Cr-Nb-Pt layer was grown by new nucleation. It exhibited reduced grain size to 10-13nm, an initial growth layer and no remarkable preferred orientation. Pt intermediate layer provided (0001) texture of Co-Cr-Nb-Pt and 20-40nm grain size by heteroepitaxial growth. TEM study revealed high stress field at the permalloy/Pt/Co-Cr-Nb-Pt interfaces. In case of Ti/Pt stacked intermediate layer the Ti (5nm) interrupted heteroepitaxy. It provided high nucleation density and reduced grain size of the Pt (10nm) intermediate layer of preferred (111) orientation. These conditions favoured (0001) orientation and 10-16nm grain size of the heteroepitaxially grown Co-Cr-Nb-Pt recording layer. The increased coercivity of the Co-Cr-Nb-Pt layer on the Pt intermediate is attributed to stress induced anisotropy.
