ELECTRONIC AND MAGNETIC-PROPERTIES OF FE-CU SUPERLATTICES

The electronic and magnetic properties of Fe/Cu superlattices grown in the (111) direction, for which Fe takes the FCC structure, are studie d with a parametrized tight-binding Hamiltonian. The splitting between majority and minority d bands is related to an effective exchange par ameter J that we adjust to obtain within our model the bulk magnetizat ion for BCC Fe. As the magnetization of bulk FCC Fe is very sensitive to this parameter we study the magnetic properties as a function of it . We find that the 2Fe/2Cu superlattice is possibly ferromagnetic and that 3Fe/3Cu has more than one stable state (paramagnetic, ferromagnet ic or ferrimagnetic) with quite similar energies. As recent experiment al results detect a small magnetic moment for this last superlattice, comparison with the calculations suggest that they are ferrimagnetic. Comparison with calculations for 2Fe and 3Fe FCC(111) free-standing sl abs show that the 2Fe/2Cu and 3Fe/3Cu superlattices behave as low-dime nsional systems, the effect of Cu being to slightly reduce the magneti c moment per atom of Fe with respect to a free-standing slab.