Microstructure and magnetic properties of granular CoPtCr-SiO₂ films on Ru seed layer

Granular-type [(Co₉₀Cr₁₀)₈₅Pt ₁₅]_89.8-[SiO₂]_10.2 films were prepared by using co-sputtering methods, with Ru as a seed layer. Influences of Ru thickness on the microstructure and magnetic properties of the CoPtCr-SiO₂ magnetic layer were investigated. It was found that the seed layer obviously effected the grain isolation, c-axis distribution and magnetic parameters. The Ru seed layer with a suitable thickness is very helpful for achievement of high anisotropy, proper coercivity and high squareness. The anisotropy energy of the magnetic layer can be as high as 5 × 10 ⁶ erg/cm³ or more, even with a thin Ru layer, promising good thermal stability. It was noted that the Ru layer markedly enhanced the isolation of CoPtCr grains, corresponding to the increase of coercivity and the decrease of loop slope. Moreover, it was also revealed that the addition of SiO₂ to CoPtCr effectively isolated the CoPtCr grains without disturbing the epitaxial growth of CoPtCr grains on the Ru seed layer.