Stacked Structure Media for High Density Perpendicular Recording

Perpendicular magnetic recording media with a new stacked media structure are proposed in this study. A distinct magnetically isolated granular Co-Pt-TiO₂ film and a Co-Pt top layer for controlling an exchange coupling of the granular film were used to realize the stacked layer. By adding the top Co-Pt layer, H_s (saturation field) becomes small with reduced DeltaH_c/H_c (narrower magnetic anisotropy distribution) and increased K_uV/k_BT (enhanced thermal stability). By changing Ar gas pressure of the top layer deposition, the exchange coupling of the granular layer could be precisely controlled. Film microstructure analysis revealed that a Co-Pt top layer deposited at high Ar gas pressure forms a granular structure. On the other hand, low gas pressure deposition formed a continuous structure with grains connected each other similar to a continuous layer of the CGC (coupled granular continuous) media