The compositional and structural stability of UHV-grown ultrathin cobalt films on Cu(111) are investigated by low-energy ion scattering. Even at room temperature migration of copper substrate atoms onto the cobalt film by surface diffusion occurs during and after the deposition process. The resulting film and interface structure therefore depends critically on deposition rate and temperature as well as on time of measurement. Our findings provide an explanation for the controversial results on structural and magnetic properties of Co/Cu films and multilayers.

• Received 26 April 1994

DOI:https://doi.org/10.1103/PhysRevLett.73.2728