EVALUATION OF THE COCRTAPT ALLOY FOR LONGITUDINAL MAGNETIC RECORDING

A quaternary alloy of CoCrTaPt with a composition of 80-10-4-6 (in at. %) was evaluated for its magnetic and recording properties. Samples o f C/CoCrTaPt/Cr recording media were prepared by dc magnetron sputteri ng on circumferentially textured Al/NiP substrates. The effects on sta tic magnetic properties and recording performance were studied for dif ferent substrate preheating times, Cr underlayer thicknesses, and Co-a lloy layer thicknesses. It was found that both the coercivity H(c) and remanent magnetization M(r) increased with substrate preheating time. H(c) also increased with Cr underlayer thickness, as expected. The M( r)delta value depended linearly on the Co-alloy layer thickness. In ad dition, we found that the coercivity increased dramatically as the mag netic layer thickness decreased from approximately 800 to approximatel y 200 angstrom. For a sample with a 235-angstrom CoCrTaPt magnetic lay er and approximately 1000-angstrom Cr underlayer, the coercivity was f ound to be >2700 Oe. Parametric evaluation showed that CoCrTaPt sample s have performance similar to samples of CoCrTa and, because of the Pt addition, the CoCrTaPt alloy offers significantly higher attainable c oercivities than the CoCrTa alloy. Therefore, the CoCrTaPt alloy prove s to be a good candidate for use in high density recording media which require coercivity of higher than 2000 Oe.