Microstructure, magnetic properties and their seed layer thickness dependences of granular CoPtCr–SiO2 perpendicular recording media

[(Co90Cr10)85Pt15]89.8–[SiO2]10.2 granular films were prepared by using co-sputtering methods, with Ru as a seed layer. Influences of Ru thickness on microstructure and magnetic properties of CoPtCr–SiO2 magnetic layer were investigated. It was found that the seed layer obviously effected the grain isolation, c -axis distribution and magnetic parameters. Ru seed layer with suitable thickness is very helpful for achievement of high anisotropy, proper coercivity and high squareness. The anisotropy energy of magnetic layer can be as high as 5×106 erg/cm3 or more even with a thin Ru layer, promising good thermal stability. It should be noted that Ru layer markedly enhanced the isolation of CoPtCr grains, corresponding the increase of coercivity and the decrease of loop slope. Moreover, it was also revealed that it was relatively easy for the CoPtCr grains to oriented normal to the film plane even with a Ru seed layer as thin as 3 nm.