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We have investigated Co/Pd multilayers deposited on either Ta or indium tin oxide ͑ITO͒ seed layers as a potential perpendicular recording media. We have examined the microstructural evolution of the films deposited on the two different types of seed layers and related it to the magnetic properties of the films. Ta underlayer produces a strong ͗111͘ fiber texture in the multilayer while ITO produces randomly oriented grains. Transmission electron microscopy reveals a microstructure of columnar grains separated by less dense material at the boundaries for the multilayers with an ITO underlayer. However, the less dense material is absent when using a Ta underlayer. The films exhibited strong perpendicular anisotropy and a higher coercivity of ϳ6800 Oe and squareness of ϳ0.99 are obtained for the films deposited on an ITO seed layer. The differences in the value of coercivity and squareness in the films can be correlated with the differences in the evolution of microstructures for different seed layers.

Deposition of films with controlled gradients across the wafer in terms of both composition and thickness were used together with statistical experimental design methodologies to explore large parameter spaces relevant to the optimization of perpendicular magnetic recording media. With this approach, thickness and composition of the media and the interdependencies of these variables were efficiently investigated and correlated to the coercivity of the material and the squareness of the hysteresis loops. To determine dependencies and codependencies between additives to CoCr alloys on the magnetic properties, this method was used to study magnetic layers of CoCrPt, CoCrPtTa, CoCrPtTi, and CoCrTiTa. The best models associated with each alloy had the same terms for the three magnetic parameters measured (Hc, S, and θk,perp). Additions to the CoCr alloy introduced dependencies on the Cr and cross-term dependencies with Cr (i.e., CrTa, CrPt, or CrTi). In some cases, thickness became an important parameter and for the CoCrPtTa case, the Pt concentration directly influenced the magnetic properties. These findings, obtained in a concise manner with fully descriptive empirical models, agree with the bulk of published literature. In this study, the variables are tightly controlled and variables such as temperature and residual gas concentrations are identical for all data points used within each alloy system generating an accurate transfer function. Once the transfer function between the input and output parameters is established, the sensitivity or stability to changes in the different factors can easily be investigated.

The effects of the Ru x Cr 1Ϫx /Ta underlayer on the microstructural and magnetic properties of CoCrPtB perpendicular films were investigated. The hcp Ru x Cr 1Ϫx ͑0002͒ texture was observed to grow perpendicular to the film plane with narrow rocking curves of 2°-3°. High-resolution transmission electron microscopy indicated epitaxial growth of the CoCrPtB on top of the Ru x Cr 1Ϫx /Ta underlayer. In-plane x-ray diffraction scans indicate that as the Cr atomic composition increases in the Ru x Cr 1Ϫx underlayer, the a-lattice parameter was found to contract more closely matching the CoCrPtB a-lattice parameter ͓measured with (112 0)͔. In addition, the rocking curves for the CoCrPtB ͑0002͒-texture induced by the ͑0002͒ textured Ru x Cr 1Ϫx buffer showed narrowing peaks (4.5°-3.5°) as the Cr concentration increased from 0% to 40%.