Enhancement of grain isolation in CoPtCr-SiO
2/Ru perpendicular recording media is discussed in relation to SiO
2 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 SiO
2 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 SiO
2 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 SiO
2 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 SiO
2 during film deposition as a result of the increase in SiO
2 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 SiO
2 perpendicular recording media.
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