Magnetic properties of cobalt films grown on a Si(100) substrate were investigated using the magnetooptic Kerr effect technique. The longitudinal coercivity for the films with a thickness range from 2.4 to 17.7 nm is observed to be approximately 55 Oe. The easy axis of magnetization is in the surface plane. Because of silicide formation at the interface and a short absorption length for light in condensed matter, the Kerr intensity is not completely proportional to the film thickness. Thermal evolution for the Co/Si(100) system was systematically investigated. A higher thermal stability is concluded for a thicker cobalt film. At a low temperature, the Kerr intensity is nearly maintained constant upon annealing treatment. This is expected to be due to the Co–Si compound at the interface blocking further interdiffusion.

A cobalt bilayer film was deposited on a monolayer (ML) Ni/Pt(111) surface at room temperature. The dependencies of the structural and magnetic properties of the surface on the annealing temperature were investigated. During the annealing, it was found that the formation of Co–Ni alloy occurs before the formation of Co–Ni–Pt alloy. After high-temperature annealing, the surface consisted of Co–Ni–Pt alloys with a Pt-rich phase. We found that the perpendicular magnetic anisotropy (PMA) contribution of the Co–Ni–Pt alloy at the surface was greater than that of the Co–Pt alloy below. The ultraviolet photoelectron spectrum (UPS) of the 2 ML Co/1 ML Ni/Pt(111) system showed a redistribution of electron density on the surface after annealing. The UPS peak height near the Fermi edge was mostly dependent on the surface composition. However, the change in the work function was not dependent on the PMA after high-temperature annealing. The strength of the PMA of this system can be tuned to a desired level by annealing without affecting the work function.