Anomalous scaling in heteroepitaxial island dynamics on Ag(100)

Diffusion and decay of alloyed Cu/Ag islands are investigated in the size range from 1 to 40 nm2 on Ag(100) at room temperature with fast-scanning tunneling microscopy and density functional theory. While islands at sizes above 7 nm2 show the diffusion and decay behavior expected for dynamics based on single atom hopping, islands smaller than 4 nm2 diffuse faster and decay slower than predicted by standard theory. This anomalous behavior at unexpected large island sizes is related to a size dependent dealloying of the Cu/Ag islands.