Electron spectroscopic imaging analysis of compositional inhomogeneity in CoCrTa longitudinal thin film media

The topographical nature of the compositional inhomogeneity in 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 20-30 at.%, and that of the Cr depleted region was in the range 5-10 at.% for the sample Ts=270°C. A strain-free CoCrTa(112¯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