Structural study of alloy formation at the Co-Pt(111) interface

This study examines the structure of the surface alloys that form at the surface of the system formed by depositing cobalt on the clean Pt(111) surface. Using mainly XPD as a structure-sensitive technique, surface alloys were observed to form in this system after annealing at temperatures of about 600 K or higher. When starting with a single atomic layer of cobalt, diffusion leads to a surface phase where Pt atoms occupy mainly the topmost layer while cobalt atoms are mainly located in the second layer from the surface. Multi-atomic-layer alloying, with the formation of an epitaxial, random substitutional Pt-Co alloy, is observed at higher temperatures.