Magnetic Properties and Microscopic Structures of Ultrathin Co/p3 × p3 − R30˚-Ag/Si(111) Films

Combined scanning tunneling microscopy and surface magneto-optic Kerr effect studies were employedto study the relation between magnetic properties and the microscopic interfacial structuresof ultrathin Co/p3×p3−R30˚-Ag/Si(111) films. On the top of p3×p3−R30˚-Ag/Si(111), pureCo clusters formed without disrupting the p3 × p3 − R30˚ structure of the Ag buffer layer. Thegreat strain due to the large mismatch between Co and the substrate influenced the nucleation ofCo atoms to form large clusters. No magnetic hysteresis in the polar configuration was observed forfilms thinner than 10 monolayers. The easy axis of magnetization was in the surface plane. Cappingp3 × p3 − R30˚-Ag on top of the Si(111) surface before the deposition of the Co overlayerscan efficiently reduce the nonferromagnetic Co-Si compound to zero thickness. For Co coveragebetween 2.9 and 4.2 monolayers, a lower Curie temperature was observed in ultrathin films. Due tothe existence of a smooth interface between Co and the p3 × p3 − R30˚-Ag buffer, the coercivityfor Co/p3 × p3 − R30˚-Ag/Si(111) is smaller than that for Co/Si(111). KCI Citation Count: 2