Edge states propagating from a defect of graphite: Scanning tunneling spectroscopy measurements

Abstract

We report nonuniform and long-range electronic perturbation of graphite near the Fermi level by the point defect based on the measurements with scanning tunneling spectroscopy. The states propagate with threefold symmetry perpendicular to the zigzag edges at the point defect, indicating the formation of the nonbonding states. The propagation continues for 3--4 nm from the defect and is accompanied by oscillations in the state energy and state intensity with a periodicity of $(\sqrt{3}\ifmmode\times\else\texttimes\fi{}\sqrt{3})R30\ifmmode^\circ\else\textdegree\fi{}$. The oscillation in the state intensity is ascribed to the disruption in the $\ensuremath{\pi}$-conjugated system in graphite around the defect, i.e., edge-states propagation from the defect while the oscillation in the state energy is ascribed to electron-electron interactions between the nonbonding $\ensuremath{\pi}$ electronic states and the standing-wave caused by $\ensuremath{\pi}$ bands of graphite.