Scanning tunneling microscopy investigation of CoO/Fe(001) and Fe/CoO/Fe(001) layered structures

We report on the nanometer scale morphology of CoO thin films grown on top of Fe(001) substrates from the early stages of interface formation (few atomic layers), and on the surface topography of Fe/CoO/Fe(001) layered structures. The growth of the CoO films is dominated by formation of islands up to about 5 nominal atomic layers, then it proceeds in the layer-plus-island regime. The surface topography of thin Fe films grown on top of the CoO/Fe systems is strongly influenced by the morphology of the latter. Moreover, we observe a strong relationship between the growth mode and the chemical interactions at the CoO/Fe interface, since thick layers of iron oxides develop only below the CoO islands, as an effect of the proximity between Fe and Co atoms. We finally discuss possible implications of our observations on the magnetic properties of these layered magnetic structures.