Dependence of the Coercive Squareness on the Recording Characteristics of CoPtCr-SiO2 Perpendicular Magnetic Recording Media

The dependence of the coercive squareness S* on the recording characteristics of CoPtCr-SiO2 perpendicular magnetic recording media was investigated. Experimental results showed that the magnetic cluster size dcl, which is evaluated by observing the ac-erased magnetization pattern of media, decreased with a decrease in S*. Ac-erased noise increased with an increase in S*. At a recording density of 1000 kfci, the S/N of a medium with S* of 0.39 was 5 dB higher than that of a medium with S* of 0.44. The recording magnetization pattern was obtained for a medium with S* of 0.39 at a high recording density of 1300 kfci. Thermal decay of the medium became very small for S* of less than 0.37. It was concluded that S* was effective parameter on the recording characteristics of CoPtCr-SiO2 perpendicular magnetic recording media.