Doubling of the orbital magnetic moment in nanoscale Fe clusters

Magnetic circular dichroism has been used to study the orbital and spin mom ents in supported nanoscale Fe clusters deposited in situ from a gas aggreg ation source onto highly oriented pyrolitic graphite in ultrahigh vacuum. M ass-filtered (2.4 MI, 610 atoms) and unfiltered (1-5 nm, 40-5000 atoms) clu sters at low coverage have an orbital magnetic moment about twice that of b ulk Fe. With increasing coverage the orbital moment of the unfiltered clust ers converges to the bulk value. There is no detectable change in the spin moment as a function of coverage. Mass-filtered clusters show an increase i n the magnetic dipole moment which we ascribe to distortion resulting from their higher impact energy. An increasing magnetic remanence with coverage is found. [S0163-1829(99)02225-0].