Magnetic and structural investigations of ultra-thin Co-Fe alloy films on W(110)

We investigated ultra-thin CoxFe1-x films on a flat and vicinal BCC W(110) surface with thicknesses between 1.8 and 7 monolayers (ML) using longitudinal Kerr magnetometry. We found a transition from magnetic bulk behavior between 3 and 4 ML to the monolayer. The maximum of the remnant Kerr signal that appears for thicker films at x = 0.5 turns into a minimum for a sample thickness below 4 ML, while the specific Kerr-rotation per monolayer shows the well known bulk behavior. A similar magnetic behavior on the flat as well as on the stepped part of the substrate indicates that this is an intrinsic property. For x = 0.5 the pseudomorphic monolayer is paramagnetic even when it is covered by ferromagnetic material. (C) 2004 Published by Elsevier B.V.