Optimization of the Thickness Ratio of Pd/Si Intermediate Layer in Co/Pd Multilayer Perpendicular Magnetic Recording Medium

Abstract

The effect of the thicknesses of Pd and Si films in the Pd/Si dual intermediate layer on magnetic properties of the Co/Pd multilayer for double-layered perpendicular magnetic recording medium was studied with the aim of developing an ultra-thin intermediate layer for producing fine magnetic clusters in the Co/Pd multilayered film. The magnetic properties were found to be strongly dependent on the ratio of the Pd or Si layer thickness to the total thickness of the Pd/Si dual film. When the ratio of the Pd layer thickness to the total thickness was 0.7-0.8, high perpendicular coercivity and small slope parameter of the major hysteresis loop were attained simultaneously, which resulted from weak intergranular exchange coupling of the Co/Pd multilayered film. In addition, the total thickness of the Pd/Si intermediate layer was successfully reduced to 4 nm, while retaining its high perpendicular coercivity and fine magnetic clusters, by optimizing the thicknesses of Pd and Si layers. Read-write experiments revealed that improvements in reproducing resolution and signal-to-noise ratio of the Co/Pd multilayered media were achieved by the decrease in the intermediate layer thickness.