Recording characteristics of single-layer perpendicular media using ring-shaped heads

On-track signal and noise characteristics of CoCr-alloy single-layer perpendicular recording media have been investigated by using three types of ring-shaped heads for writing and an MR head for reading. The output signal is improved with decreasing the write-gap length of ring-shaped head. The D₅₀ and the S/N ratio at 200 kFCI are respectively improved by 59 kFCI and 5.7 dB, when the write-gap length is decreased from 0.40 to 0.22 μm. When the recording characteristics of CoCrTa, CoCrPt and CoCrPtTa media are compared by using narrow-gap write head, it is clarify that the CoCrTa medium indicates the S/N ratio higher than 29 dB at 400 kFCI, and that the CoCrPt and the CoCrPtTa media shows the D₅₀ value higher than 235 kFCI. The medium noise of the CoCrPt or the CoCrPtTa at high recording density should be reduced by improving the recording layer