Directed long-range transport of a nearly pure component atom clusters by the electromigration of a binary surface alloy

A continuum model for electromigration-driven transport of an embedded, compact atom cluster across a surface terrace of a phase-separating binary surface alloy is presented. Computations show that the electron wind reliably transports the cluster over hundreds of lattice spacings and in the set direction, while the cluster purity improves during the drift. Impacts on cluster's drift speed and purity of the A to B atom's jump frequencies ratio, the magnitude and the sign of the A and B atoms's effective surface charges, the applied voltage, and the diffusion anisotropy are studied.