  The effective exchange interactions of magnetic overlayers Fe/Cu(001) and
Co/Cu(001) covered by a Cu-cap layer of varying thickness were calculated in
real space from first principles. The effective two-dimensional Heisenberg
Hamiltonian was constructed and used to estimate magnon dispersion laws,
spin-wave stiffness constants, and overlayer Curie temperatures within the
mean-field and random-phase approximations. Overlayer Curie temperature
oscillates as a function of the cap-layer thickness in a qualitative agreement
with a recent experiment.
