Magnetic and recording properties of sputtered Co-P/Cr thin film media

Sputtered Co-P/Cr longitudinal media exhibiting high recording densities with low transition noise were investigated. Linear recording densities >25 KFCI and SNR >31 dB were obtained with a thin-film head having 14-μm track width and 0.25-μm gap, and flying at 0.15 μm. The magnitude of the recorded transition noise depended strongly on the thickness of the Cr underlayer and the coercive squareness of the Co-P films. A strong dependency of transition noise on the film phase structure was found; Co alloys that could form two phases were from 3-5 times to as much as 10 times quieter than alloys that formed only a single phase. This behavior is interpreted in terms of the presence or absence of ferromagnetic exchange between grains, which when present leads to long-range collective behavior and high transition noise