Magnetic properties and microstructure of Co80Pt20-30 vol.% (Al2O3, TiO2, WO3) and Co82.4Pt17.6-27.7 vol.% SiO2 granular films postannealed at various temperatures in a heat-treating furnace were investigated. In this paper, it is found that among these granular films, CoPt-WO3 granular film shows the highest coercivity (Hc) because of low intergranular exchange coupling of well-isolated magnetic grains. Furthermore, the Hc is enhanced with postannealing because of the increase of the magnetic anisotropy field (Hkgrain) and uniaxial magnetocrystalline anisotropy (Kugrain) of the columnar growth magnetic grains. The increase of Kugrain for the postannealed granular film primarily originates from the reduction of the stacking faults as well as the lattice constant ratio.
- CoPt-WO granular film
- high K
- perpendicular magnetic recording