High dipolar magnetic moment observed on Ni/Cu(1 1 1) nanostructures by magnetic circular X-ray dichroism

Morphology studies at the first stages of the growth of Ni/Cu(1 1 1) are reported and compared to the magnetic properties of the nanostructures. In the early stages of the growth the nickel morphology shows 10–30 nm large triangular islands monolayer height. In addition stripes are formed at the step edges via a step flow growth mode. The particular shape of the oriented triangular islands has been examined by scanning tunneling microscopy and the segregation of Cu atoms has been evidenced on top of the Ni islands after a critical deposit amount at 0.8 ML. It is shown that both the morphology of these nanostructures and the Cu diffusion have a strong influence on the magnetic properties as evidenced by magnetic circular X-ray dichroism. We show that even for sub-monolayer coverages the Ni/Cu(1 1 1) films are magnetic. The evolution of the size and composition of the islands during the growth can be correlated with the evolution of the magnetic moments and strong dipolar magnetic moments are related to the formation of a second Cu/Ni interface.