ELECTRON SPECTROSCOPIC IMAGING ANALYSIS OF COMPOSITIONAL INHOMOGENEITY IN COCRTA LONGITUDINAL THIN-FILM MEDIA

The topographical nature of the compositional inhomogeneity in the Co-17at%Cr-5at%Ta/Cr longitudinal thin film media deposited at different substrate temperature Ts, was analyzed using electron spectroscopic imaging. In the CoCrTa film deposited at high Ts, Cr segregates to the grain boundaries and intragrains, resulting in a two-dimensional network. The compositional variation grew as Ts became high. The concentration of the Cr enriched region was in the range of 20-30at%, and that of Cr depleted region was in the range of 5-10at % for the sample Ts=270 degrees C. A strain-free CoCrTa(<11(2)over bar 0>) lattice spacing, which is probably related to the Cr concentration in the Co hexagonal matrix, decreased as Ts became high. This Cr segregation can reduce the exchange coupling between neighboring grains, resulting in low noise characteristics.