Supported fe nanoclusters: evolution of magnetic properties with cluster size.

Using a density functional approach, we study structural and magnetic properties of small Fe(n) clusters (n<or=8) deposited on a MgO(100) substrate. Upon deposition, the clusters closely preserve their gas-phase structure. The magnetic moments for the adsorbed clusters exceed the value for bulk Fe. Compared to the gas phase, significant reductions in the magnetic moments are found for Fe(n) clusters with n<or=6. These reductions result from intracluster charge rearrangements caused by interaction with O 2p orbitals, rather than from structural deformations or charge transfer from the surface. As the cluster size increases, the gas-phase magnetic moments are recovered.