Co Alloy- ${\hbox{SiO}}_{2}$ Granular-Type Longitudinal Media for Sputtered Tape Applications

We investigated bias-sputtered Co alloy-films (CoCrPt- and CoPt-) for high density magnetic tape media. We used bias sputtering to achieve desirable properties (good in-plane orientation and low noise) in these media. The CoCrPt-sputtered tape media showed a flat frequency response with a of 160 kfci and a corresponding signal-to-noise ratio of 21 dB. The overwrite performance was better than 40 dB for an overwriting frequency of 12 MHz (90 kfci) and overwritten frequency ranging from 1 to 10 MHz (8-75 kfci). An overcoat (carbon nitride) with a thickness of 6 nm resulted in a 4-5 dB spacing loss in the roll-off curve at high recording densities, and a 3-4 dB lower overwrite ratio. In addition, the CoPt-media with no Cr present produced a maximum output 4-5 dB higher, but also higher noise power compared to the CoCrPt-media.