Seedlayer and pre-heatfng effects on crystallography and recording performance of CoCrPtB perpendicular media

Summary form only given. Perpendicular magnetic recording (PMR) media has been considered as a promising candidate in order to achieve over 100 Gbir/in² recording density. However, thermal stability at low recording densities has been a concern especially for low-noise PMR media. Achieving high perpendicular H_C and unity squareness (SQ=Mr/Ms) is necessary to improve thermal stability and has been proposed by using either high substrate temperature or post annealing in CoCr based alloy. However, the influence of high heating on recording performance deserves further investigation. In this work, we studied on the seedlayer and heating effects on the crystallographic, magnetic and recording properties of CoCr₁₈Pt₁₆B₄ granular PMR media. The CoCrPtB films were sputtered on preheated glass substrates with a Ru underlayer (UL) or a Ta/Ru UL on top of a 300-nm-thick NiFe₁₇Mo₄ soft magnetic underlayer. We report that Ta/Ru UL developed in this study greatly enhances Ru(0002)/Co(0002) crystallography, H_C, SQ and thermal stability without degrading media signal-to-noise ratio (So/Nm).