Epitaxial Growth of Metastable Co-Cu Alloys by a Surface Pump Mechanism

We report the operation for Co-Cu alloys of a surface pump mechanism whereby bulk metastable alloys are formed during epitaxial growth. This happens when a material with a larger surface energy (Co) is grown on a film with a lesser surface energy (Cu). The specific pathway transports Cu through pinholes by surface diffusion at temperatures which are too low for the metastable alloy to decompose by bulk diffusion.