Effect of Ag buffer layer to ultrathin Co films on Si[111] surface

The magnetic properties of ultrathin Co/Ag/Si[111] films were studied by surface magneto-optic Kerr effect. A magnetic phase diagram for binary-metal Co/Ag films deposited on Si[111] surfaces has been successfully established. The phase diagram can be divided into four regions: nonferromagnetic Co-Si compound; low Curie temperature Co film; canted out-of-plane anisotropy; in-plane anisotropy. The ferromagnetic inactive layers at the Co/Si interface are formed due to intermixing of Co and Si; and can be efficiently reduced by the Ag buffer layer. We have demonstrated that the inactive layer thickness is reduced from 2.1 ML for Co/Si[111], to 1.0 for Co/2.8 MLAg/Si[111], and 0.0 for Co/5.6 MLAg/Si[111].