Super-periodic patterns near to a step edge were observed, by scanning tunneling microscopy, on several-layer thick graphite sheets on a highly-oriented pyrolitic graphite substrate. A dislocation network was generated at the interface between the graphite overlayer and the substrate. Triangular- and rhomb-shaped periodic patterns, whose periodicities were about 100nm, were observed on the upper terrace near to the step edge. Only outlines of patterns, similar to those on the upper terrace, were observed on the lower terrace. On the upper terrace, the geometrical patterns gradually disappeared and became similar to those on the lower terrace; without any changes in their periodicity with increasing bias voltage. By assuming a periodic scattering potential at the interface, due to dislocations, the varying corrugation amplitudes of the patterns could be understood as being changes in the local density of states as a result of the beating of perturbed and unperturbed waves (i.e. interference). The observed changes in the image, depending upon overlayer height and bias voltage, could be explained by electronic wave interference in the ultra-thin overlayer; as distorted by the influence of dislocation-network structures.

STM Observation of Electronic Wave Interference Effect in Finite-Sized Graphite with Dislocation-Network Structures. Y.Kobayashi, K.Takai, K.Fukui, T.Enoki, K.Harigaya, Y.Kaburagi, Y.Hishiyama: Physical Review B, 2004, 69[3], 035418 (7pp)