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 of C/CoCrTaPt/Cr recording media were prepared by dc magnetron sputtering on circumferentially textured Al/NiP substrates. The effects on static magnetic properties and recording performance were studied for different substrate preheating times, Cr underlayer thicknesses, and Co-alloy 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 addition, we found that the coercivity increased dramatically as the magnetic layer thickness decreased from approximately 800 to approximately 200 angstrom. For a sample with a 235-angstrom CoCrTaPt magnetic layer and approximately 1000-angstrom Cr underlayer, the coercivity was found to be >2700 Oe. Parametric evaluation showed that CoCrTaPt samples have performance similar to samples of CoCrTa and, because of the Pt addition, the CoCrTaPt alloy offers significantly higher attainable coercivities than the CoCrTa alloy. Therefore, the CoCrTaPt alloy proves to be a good candidate for use in high density recording media which require coercivity of higher than 2000 Oe.