On superperiodic features on highly oriented pyrolytic graphite

We present scanning tunneling microscopy (STM) results that show the superstructure on the highly oriented pryrolytic graphite (HOPG) surface. The superlattice appears to be the result of an apparent twist boundary dislocation. The crucial point of the observation is that the superlattice changes simultaneously its constant from 18 to 72 nm when we go around the screw dislocation in the plane perpendicular to the dislocation vector. Based on available models of the graphite surface top layers, we are able to simulate observed STM images. Our STM observation of the superstructure lattice, whose lattice constant varies continuously, gives strong evidence that the superlattice is of Moire pattern nature, but a correct model can be built only if the graphite electronic structure is taken into consideration.