Magnetostriction constant of multilayer Co/Ag films

The saturation magnetostriction constant λ_s has been measured at room temperature in Co/Ag multilayer films prepared by evaporation in ultrahigh vacuum. It was found that in addition to the surface magnetostriction term, an additional one due to reduced symmetry of the magnetoelastic interaction should be incorporated to explain the peculiar dependence of λ_s on the thickness of the Co layer. The dependence of the anisotropy constant K_u on the Co-layer thickness in the films investigated resembles the dependence of λ_s, indicating that the same mechanisms are important in both cases. The results obtained are shown to be related to the reduced symmetry in the nanometer-scale multilayer films