Berlin 2015 – scientific programme

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O: Fachverband Oberflächenphysik

O 82: Nanostructure at Surfaces: Dots and Clusters

O 82.3: Talk

Thursday, March 19, 2015, 11:00–11:15, MA 043

STM and STS study of Tb induced magic clusters on Si(111)7x7 — •Jan Große, Martin Franz, and Mario Dähne — Institut für Festkörperphysik, Technische Universität Berlin, 10623 Berlin, Germany

Surface clusters constitute a promising new research field in solid state physics due to their interesting quantum properties and possible future applications in nanodevices and catalysis. In this work, scanning tunneling microscopy (STM) and spectroscopy (STS) was used to study Tb induced clusters on the Si(111)7x7 surface. The samples were prepared by molecular beam epitaxy using submonolayer Tb coverages and annealing at moderate temperatures. It was found that the self-organized growth of clusters occurred in the center of the 7x7 half unit cells. These clusters have a triangular shape, but do not show the mirror symmetry of the half unit cell, thus they form one of the two equivalent rotated configurations. Furthermore, the ability of tip-induced switching between these two configurations was demonstrated. From atomically resolved STM images a structure model explaining nicely our observations could be developed. Additionally, STS measurements were performed in order to compare the electronic structure of the centered clusters with the surrounding Si(111)7x7 surface.

This work was supported by the DFG, FOR 1282, project D.