Interdiffusion and magnetism in Cu/Ni/Cu sandwiches

Results are presented for the magnetic-moment distribution in a (111) sandwich consisting originally of three perfect layers of nickel bounded on each side by a semi-infinite copper crystal, for different degrees of interdiffusion. The approach used is a combination of the recently developed layer Korringa-Kohn-Rostoker method, with the multiple-scattering spin-polarized version of the coherent-potential approximation. When applied to bulk homogeneous Cuₓ{Ni}_{1{{-}}x}$, it yields average and Ni moments in excellent agreement with experiment. The sandwich geometry is found to favor magnetism at Ni concentrations far below the bulk critical value.