Magnetism of 3dtransition-metal monolayers and two-dimensional Cr clusters deposited on Fe(001)

We study the magnetic properties of transition-metal monolayers (ML) and Cr clusters deposited on Fe(001). We use a self-consistent tight-binding model and the recursion technique in order to get the most stable magnetic state for each atomic configuration. The magnetism is taken into account in the mean-field approximation. We show that for a Cr ML the p(2×{}2) magnetic solution is lower in energy than all the others. We find that monolayers of V, Ni, and Co are ferromagnetic p(1×{}1) on Fe(001) whereas the Mn ML are c(2×{}2) antiferromagnetic. We study also the magnetic transition occurring for Cr clusters, for an increasing Cr atoms number, from ferromagnetic to the p(2×{}2) order. The results of these calculations are in agreement with those of an Ising model whose parameters are determined. Such an Ising model predicts with a good accuracy the most stable state and the first excited states for each cluster shape. {} 1996 The American Physical Society.