The crystal structure, microstructure, and magnetic properties for a series of Cu/FePt bilayer films were investigated. The samples were prepared by depositing a Cu top layer on a highly ordered L10 FePt film. To promote interdiffusion, the bilayer samples were annealed at 300 to 800C. X-ray diffraction data indicate that observable diffusion occurred at 400C. The maximum coercivity thus obtained was 14.0kOe, which was 24% larger than that of the ordered FePt film without a Cu top layer. The high Hc could be attributed to the diffusion of Cu atoms through the grain boundaries of the magnetic films, which may produce extra pinning sites for domain-wall movement. The ΔM data measured from the Henkel plots of annealed Cu/FePt films change from negative to positive values as the annealing temperature was raised from 400 to 800C. This could result from the effects of demagnetization coupling and exchange coupling and was further explained from the variation of squareness ratios of hysteresis loops.

Effect of Interfacial Diffusion on Microstructure and Magnetic Properties of Cu/FePt Bilayer Thin Films. S.K.Chen, F.T.Yuan, T.S.Chin: Journal of Applied Physics, 2005, 97[7], 073902 (6pp)