  We present ab-initio calculations of the magnetic moments and magnetic
anisotropy energies of small FeCo clusters of varying composition on top of a
Cu(100) substrate. Three different cluster layouts have been considered, namely
2x2, 3x3 and cross-like pentamer clusters. The ratio of Co atoms with respect
to the total number in a chosen cluster (``concentration'') was varied and all
possible arrangements of the atomic species were taken into account.
Calculations have been performed fully relativistically using the embedded
cluster technique in conjunction with the screened Korringa-Kohn-Rostoker
method and the magnetocrysergy depend on the position they occupy in a
particular cluster and on the type and the number of nearest-neighbors. The MAE
for the 2x2 and 3x3 clusters varies with respect to the ``concentration'' of Co
atoms in the same manner as the corresponding monolayer case, whereas the
pentamer clusters show a slightly different behavior. Furthermore, for the
clusters with an easy axis along a direction in the surface plane, the MAE
shows a significant angular dependence.
