Interaction of Dysprosium with the Basal Plane of Graphite.

We have studied adsorption, nucleation, growth, intercalation, and carburization of dysprosium (Dy) on graphite surfaces, and the way that these phenomena are influenced by surface defects. The experiments consist of scanning tunneling microscopy in ultrahigh vacuum. The condensation coefficient of Dy is strongly enhanced by surface defects. In the absence of defects, at room temperature, homogeneous nucleation can occur on terraces, consistent with DFT calculations of energetics. At room temperature, island shapes consist of a flat three-atom base, decorated by single-atom upper layers. Layer populations in such islands are analyzed in the context of a tailored analytic model, which provides information about interlayer mobility. At elevated temperature, Dy can intercalate with the graphite substrate and can form carbide.