New high coercivity cobalt alloy thin film medium structure for longitudinal recording

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Abstract
A combined underlayer of (110) textured Cr and a hexagonal close-packed (HCP) Co or CoCrTa intermediate layer yields an improved CoCrPt recording media. The addition of Pt greatly increases the coercivity of the cobalt films but also expands the lattice of Co alloys preventing a good lattice match to the Cr underlayer. However, HCP Co and CoCrTa lattice match reasonably well to Cr. It is shown that an intermediate HCP layer, as thin as 50 Å, provides a HCP template upon which (10.1) CoCrPt texture can develop, resulting in suppressed (00.2) texture. By adjusting the relative layer thicknesses, coercivities between 1700 and 4200 Oe are controllably obtained for an independent variety of Mrt values.