Profiles across a linear interface which separated 2 metals that were miscible as monolayers - Co and Cu on a (00•1) Ru surface - were measured as a function of time. It was found that the interface remained sharp even after substantial intermixing. This was in marked contrast to the interdiffusion behavior of bulk miscible metals. The present concentration profiles were explained in terms of a combination of adatom surface diffusion and exchanges of adatoms with atoms in the monolayer films. A simple Monte Carlo simulation of the adatom exchange mechanism gave quantitative agreement with observations.

A.K.Schmid, J.C.Hamilton, N.C.Bartelt, R.Q.Hwang: Physical Review Letters, 1996, 77[14], 2977-80