Abstract
Enhancement of grain isolation in CoPtCr-SiO2/Ru perpendicular recording media is discussed in relation to SiO2 the content and grain size of the Ru seed layer. The value of the remanence coercivity obtained by subtracting the thermal agitation effect, H0, increases significantly with increasing SiO2 content up to ∼ 11 at%, indicating enhancement of the grain isolation of CoPtCr. TEM images revealed that a single CoPtCr grain grows on a Ru grain in this SiO2 content region, and experimental results showed that the grain size of the Ru seed layer plays a dominant role in determining the grain size of CoPtCr layer. However, a further increase in SiO2 content beyond 11 at% results in a growth of multiple CoPtCr grains on a Ru grain, leading to a decrease in H0. The formation of the multiple CoPtCr grains was remarkable on large Ru grains, suggesting a significant reduction of the diffusion length (mobility) of SiO2 during film deposition as a result of the increase in SiO2 content. Both a grain size reduction and an improvement in grain size homogeneity are required for a Ru seed layer to enhance the grain isolation in CoPtCr SiO2 perpendicular recording media.
