Chromium Underlayer Effects in Longitudinal Magnetic Recording

Abstract

ABSTRACTFor media used in longitudinal recording, an epitaxial relationship is observed between the Cr and Co-alloy layers, and generally a strong Cr <100> texture is desirable for c-axis in-plane orientation of the Co alloy. In this study, Cr underlayer thickness, temperature and Cr deposition pressure were varied while keeping the magnetic layer (CoPtCr) deposition process constant. Films were deposited on circumferentially textured NiP, polished NiP and chemically elched NiP substrates as well as Si wafers in order to study the effects of surface finish on the crystallographic orientation of the Cr underlayer. The uniformity of the magnetic properties and in-plane anisotropy (orientation ratio) of the disks were measured using Kerr magnetrometry. The in-plane anisotropy was found to be related to the Cr deposition conditions and the surface texture of the NiP. Signal to noise ratio results and a possible mechanism for the origin of the in-plane anisotropy are discussed.