LAUSR

We report on thefirst example of a self-assembled rare earth cluster superlattice. As a template, we use themoiré pattern formed by graphene on Ir(111); its lattice constant of 2.52nmdefines the interparticle distance. The samarium cluster superlattice forms for substrate temperatures during deposition ranging from80 to 110K, and it is stable upon annealing to 140K. By varying the samarium coverage, themean cluster size can be increased up to 50 atoms, without affecting the longrange order. The spatial order and thewidth of the cluster size distributionmatch the best examples of metal cluster superlattices grown by atomic beam epitaxy on template surfaces.