Crystallographic Structures, Magnetic Properties and Their Change Due to Annealing in Co/Cr Multilayered Films

The crystallographic structure and magnetic properties of Co/Cr multilayer films were investigated. Films are comprised of hcp Co and bcc Cr. The crystallographic structure of the film was affected by the substrate temperature, particularly in the case of small layer thicknesses. Films sputtered at high substrate temperatures had larger perpendicular anisotropy than those sputtered at low temperatures. The saturation magnetization per unit Co volume decreases with decreasing Co layer thickness. Alloying at interfaces causes the decrease of Co layer magnetization. The thickness of the alloy layers is estimated at 2.5 Å to 5.0 Å. Films prepared on glass substrates were annealed in vacuum at 300°C and 500°C. Diffusion coefficients and activation energies were calculated from the decrease in magnetization due to annealing; the activation energy for diffusion was between 0.2 and 0.5 eV.