Compositional Separation in Co-Cr Based Alloy Films

Using ⁵⁹Co nuclear magnetic resonance and a chemical etching technique, we observed that compositional separation which produces highly Co-rich precipitates occurs in (1) a Co-Cr film which exhibited ultra-high bit density in perpendicular magnetic recording and (2) Co-Cr-X (X=Ta, Pt, Ni) films for longitudinal magnetic recording. It is expected that this kind of separation will enable the compositional microstructure of Co-Cr based alloy films to be changed from a homogeneous structure to a particulate one suitable for either perpendicular or longitudinal high-density recording.