CoCrPtTa and Co/Pd perpendicular magnetic recording media with amorphous underlayers

摘要

The effect of amorphous carbon underlayers on magnetic properties and read-write characteristics of Co{sub}73Cr{sub}18Pt{sub}6Ta{sub}3 single layer and Co/Pd multilayer perpendicular magnetic recording media were investigated. The increase in H{sub}C and decrease in α, defined as 4π( dM/dH){sub}(H=HC), were observed by increasing the underlayer thickness for both Co{sub}73Cr{sub}18Pt{sub}6Ta{sub}3 and Co/Pd media. The media with a low Q value, suggesting a decrease in the exchange coupling, exhibited the higher coercivity and the improvement of SIN ratio. In read-write experiments, the improvement of S/N ratio for the Co/Pd media was achieved up to 400 kFRPI or even higher in the recording density by increasing carbon underlayer thickness, while that for the Co{sub}73Cr{sub}15Pt{sub}6Ta{sub}3 media was obtained up to ca. 250 kFRPI.