Effects of Ag buffer layer on the magnetic properties of ultrathin Co/Ge(111) films

Abstract

The influences of an Ag buffer layer on the magnetic properties of ultrathin Co/Ge(111) films grown at ambient temperature were studied using the surface magneto-optic Kerr effect technique. Due to the intermixing of Co adatoms and Ge(111) substrate, a nonferromagnetic layer forms at the initial stage of the deposition for Co/Ge(111) films. We demonstrate experimentally that the ferromagnetic inactive layer can be reduced by introducing an Ag buffer layer and the orientation of the easy axis of magnetization remains unchanged. Three magnetic phases have been resolved for Co/Ag/Ge(111) films with a Ag thickness less than 6 monolayers. In the phase diagram, the boundary between ferromagnetic and nonmagnetic regions shifts to a lower Co thickness from 10 to 5 monolayers as the thickness of the Ag layer increases from 0 to 6 monolayers.