A Monolayer of Hexagonal Boron Nitride on Ir(111) as a Template for Cluster Superlattices

The moire of a monolayer of hexagonal boron nitride on Ir(111) is found to be a template for Ir, C, and Au cluster superlattices. Using scanning tunneling microscopy, the cluster structure and epitaxial relation to the substrate, the cluster binding site, the role of defects, as well as the thermal stability of the cluster lattice are investigated. The Ir and C cluster superlattices display a high thermal stability, before they decay by intercalation and Smoluchowski ripening. Ab initio calculations explain the extraordinarily strong Ir cluster binding through selective sp(3) rehybridization of boron nitride involving B-Ir cluster bonds and a strengthening of the nitrogen bonds to the Ir substrate in a specific, initially only chemisorbed valley area within the moire.