CRYSTALLOGRAPHIC ANISOTROPY IN THIN-FILM MAGNETIC RECORDING MEDIA ANALYZED WITH X-RAY-DIFFRACTION

The crystallographic anisotropy of CoCr alloy films deposited on a Cr underlayer was investigated with grazing incidence x-ray scattering (GIXS). The effect of circumferential mechanical texturing of the NiP substrate (producing microgrooves through polishing) was explored. The Co was found to grow heteroepitaxially on the Cr underlayer with the Co(1120BAR) growth planes parallel to the Cr(001) growth planes. We observe no significant differences in Co lattice parameter in the circumferential and radial directions, although we do see variations in crystallographic texture between these two directions. From GIXS peak intensities, we observe that there is a greater population of crystallites with their c axis pointed along the grooves. This analysis was done after allowing for the effect of the varying local surface normal due to the substrate grooves. The ratio of the coercivities in the two directions scales with the ratios of the c-axis population densities. Two simple quantitative models of the magnetic properties of the aggregate have been constructed: strongly coupled grains and uncoupled grains. The predictions of these models are compared to the observed properties.