Cooperative mechanisms behind nanoscale smoothing on metal surfaces: From adatom diffusion to step nucleation

Many technologies require stable or metastable surface morphology. In this paper we study the factors that control the metastability of a common feature of rough surfaces: ``hillocks.'' We use low energy electron microscopy to follow the evolution of the individual atomic steps in hillocks on Pd(111). We show that the uppermost island in the stack often adopts a static, metastable configuration. Modeling this result shows that the degree of the metastability depends on the configuration of steps dozens of atomic layers lower. Our model allows us to link surface metastability to the atomic processes of surface evolution.