Relation between microstructure of grain boundary and the intergranular exchange in CoCrTa thin film for longitudinal recording media

In CoCrTa films, the relationship between the microstructure of grain boundaries and degree of intergranular exchange coupling was investigated. The degree of intergranular exchange coupling decreases as Ta content increases. By TEM observation, it was revealed that the boundary phase, which appears to be amorphous, surrounds the grains. The width of this boundary phase tends to become thicker as Ta content increases. From the result of an EDS analysis, the Cr content at the grain boundaries is higher than that in the grains. The boundary phase may be non-magnetic due to its high concentration of Cr. On the other hand, in this experiment, no boundary phase was observed in CoNiCr and CoCrPt films which have the higher degree of intergranular exchange coupling than CoCrTa films. Therefore, the change in the boundary phase may be effective in reducing the degree of intergranular exchange coupling.<
>