Magnetism of nanostructures studied by x-ray magnetic circular dichroism: Fe on Cu(111)

Abstract

Epitaxial growth of Fe on a stepped Cu(111) surface leads to the formation of fcc Fe stripes along the step edges for coverages lower than 1.5 monolayer (ML). Using the sensitivity of the x-ray magnetic circular dichroism and sum-rule analysis, the changes in the magnetic properties in the low thickness range from \ensuremath{\sim}5% of a monolayer to 4 ML, covering the one-dimensional (1D) coalescence (\ensuremath{\sim}0.8 ML) and the 2D percolation limit (\ensuremath{\sim}1.5 ML), have been determined. The determination of the spin moment ${(m}_{\mathrm{spin}})$ indicates significant features which can be correlated to the morphological transition. In particular, the ${m}_{\mathrm{spin}}$ decreases at the 1D coalescence limit, but increases as the film reaches the 2D percolation limit and starts to transform into the bcc phase. This behavior is tentatively ascribed to the decrease in the Fe atomic volume, as it is well known that such changes can dramatically modify the magnetic properties of \ensuremath{\gamma}-Fe.