The (110) surface of the disordered Pt25Co75 alloy: a sandwich of almost pure monoatomic layers

Abstract The (110) surface structure of the Pt 25 Co 75 alloy in the substitutionally disordered state was studied by quantitative LEED. In a way similar to Pt x Ni 1− x (110) surfaces, on the Ni rich side, the composition profile versus depth is strongly oscillating with a pure cobalt top layer; however, the oscillation is stronger and goes deeper for Pt 25 Co 75 (110) than for the previously studied surfaces of Pt 10 Ni 90 (110) and Pt 50 Ni 50 (110). Actually the selvedge, which can be easily produced by simple standard argon cleaning and annealing UHV techniques, is a sequence of three almost pure layers: CoPtCo. This provides an interesting system to be studied: the monolayer limit of PtCo sandwiches.