The importance of Pb-vacancy attractions on diffusion in the Pb/Cu(0 0 1) surface alloy

We study the diffusion of Pb atoms embedded in a Cu(0 0 1) surface using atom-tracking scanning tunneling microscopy. By comparing these observations with simulations based on first-principles electronic structure calculations, we deduce that the diffusion occurs by a vacancy-mediated mechanism in which the vacancy is attracted by the embedded Pb atom.