Effects of an Ag overlayer on the magnetic properties of ultrathin Co/Cu(111) films

The evolution of magnetic properties of ultrathin Co/Cu(1 1 1) films with A g overlayer has been investigated using the surface magneto-optical Kerr ef fect. In general, the easy axis of the magnetization is in-plane for a Co/C u(1 1 1) system. However, a small longitudinal coercive force (one order sm aller than that in polar case) has been observed for films with Co thicknes s roughly between 1.5 and 10 monolayers. With an Ag overlayer on the top of films. the orientation of the easy axis does not change. Ag-induced oscill ation of the polar coercive force shows that it is dominated by the complet e or incomplete Ag atomic layers. The oscillation phenomenon decreases with increasing the thickness of the Co layer, from 2.3 to 4.6 ML. (C) 2001 Els evier Science B.V. All rights reserved.