Interlayer exchange coupling in fine-layered Fe/Au superlattices

Interlayer exchange coupling (IEC) in Fe (n ML)/Au (n ML) superlattices (SL's) (ML's= monolayers, n = 1 to 5) has been examined by Brillouin scattering from spin waves at 300 K. The IEC was found to be ferromagnetic for all n, but the IEC strength J_i exhibits oscillatory behavior: it is large for even ML's and small for odd ML's. For n=1 which correponds to an ordered alloy with the L1₀ structure, we obtain J_i=43.6 ±5.0 mJ/m². Ab initio calculation of J_i by the self-consistent full-potential linearized augumented-plane-wave method gives a good agreement with the experimental values, except for n=3 where an antiferromagnetic ground state is predicted.