Evidence for interdot coupling in an array of micrometric Fe dots

The magnetization reversal of both the continuous and patterned Fe films, grown in ultra high vacuum by atomically controlled evaporation through a mask, was studied using magneto-optic Kerr magnetometry. The hysteresis loops recorded from continuous Fe film as a function of the direction of the applied field, evidence a well-defined uniaxial anisotropy, induced during the film deposition. The patterned area shows a magnetic anisotropy completely different from that of the continuous film and related to the lattice symmetry. Scanning electron microscopy images of the patterned area allows us to exclude effects related to deviations from circularity of the shape of the single dots. The close relationship between the anisotropy directions and the pattern lattice axes indicates that the new anisotropy originates from the interdot dipolar coupling interaction.