High-Resolution TEM Analysis of Perpendicular CoCrPt-SiO2 Media

We investigated the relationship among the grain size, the grain boundary width, and the in-plane crystallographic orientation of CoCrPt-SiO2 perpendicular media using high-resolution transmission electron microscope (HR-TEM). The average grain size in a CoCrPt-SiO2 magnetic layer and its dispersion were 7.5 nm and 18%, respectively. The width of the grain boundary was 0.68 nm in average and increased with grain size. In addition, we found a group of neighboring grains with parallel a-axes of h.c.p.-structure, which is defined as a crystal grain cluster. The grain boundary width tended to decrease as the cluster size increased. The results suggested that the size of the crystal grain cluster should be reduced for controlling the intergranular exchange coupling that presumably depends on the grain boundary width.