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 (G IXS). The effect of circumferential mechanical texturing of the NiP su bstrate (producing microgrooves through polishing) was explored. The C o was found to grow heteroepitaxially on the Cr underlayer with the Co (1120BAR) growth planes parallel to the Cr(001) growth planes. We obse rve no significant differences in Co lattice parameter in the circumfe rential and radial directions, although we do see variations in crysta llographic texture between these two directions. From GIXS peak intens ities, we observe that there is a greater population of crystallites w ith their c axis pointed along the grooves. This analysis was done aft er allowing for the effect of the varying local surface normal due to the substrate grooves. The ratio of the coercivities in the two direct ions scales with the ratios of the c-axis population densities. Two si mple quantitative models of the magnetic properties of the aggregate h ave been constructed: strongly coupled grains and uncoupled grains. Th e predictions of these models are compared to the observed properties.