Edge state on hydrogen-terminated graphite edges investigated by scanning tunneling microscopy

TL;DR

This study uses ultrahigh-vacuum scanning tunneling microscopy to investigate the spatial distribution of edge states at hydrogen-terminated zigzag and armchair edges in graphite, revealing site-dependent behaviors and defect effects.

Contribution

It provides detailed experimental observations of edge state distributions on graphite edges and confirms them with tight binding calculations based on atomic structures.

Findings

Edge states differ between $eta$- and $\alpha$-site zigzag edges.

Edge states are present near short zigzag or Klein defects.

Spatial distribution of edge states depends on local atomic structure.

Abstract

The edge states that emerge at hydrogen-terminated zigzag edges embedded in dominant armchair edges of graphite are carefully investigated by ultrahigh-vacuum scanning tunneling microscopy (STM) measurements. The edge states at the zigzag edges have different spatial distributions dependent on the $\alpha$- or $\beta$-site edge carbon atoms. In the case that the defects consist of a short zigzag (or a short Klein) edge, the edge state is present also near the defects. The amplitude of the edge state distributing around the defects in an armchair edge often has a prominent hump in a direction determined by detailed local atomic structure of the edge. The tight binding calculation based on the atomic arrangements observed by STM reproduces the observed spatial distributions of the local density of states.