# Intrinsic superstructure near atomically clean armchair-type step edge of graphite

## TL;DR

This study uses scanning tunneling microscopy to analyze the electronic superstructure near atomically clean armchair step edges of graphite, revealing a specific superstructure pattern and clarifying the coexistence of different superstructures.

## Contribution

It demonstrates that the ($
abla3\times\nabla3$)$\textit{R}$30$^{\circ}$ superstructure is dominant near clean armchair edges and explains the coexistence of superstructures near defective edges.

## Key findings

- Only the ($\sqrt{3}\times\sqrt{3}$)$\textit{R}$30$^{\circ}$ superstructure appears near clean edges.
- The superstructure pattern results from superposition of two superstructures with different phases.
- The study clarifies the coexistence of superstructures near defective edges.

## Abstract

We investigated the electronic superstructure of graphite surface in the vicinity to monoatomic armchair step edges with scanning tunneling microscopy and spectroscopy. Only the ($\sqrt{3}\times\sqrt{3}$)$\textit{R}$30$^{\circ}$ superstructure is visualized near atomically clean armchair edges, while the honeycomb superstructure is absent. The spectroscopic mapping near the clean armchair edge clearly reveals the ($\sqrt{3}\times\sqrt{3}$)$\textit{R}$30$^{\circ}$ superstructure on both sides of the step edge. We have also visualized a mixture of ($\sqrt{3}\times\sqrt{3}$)$\textit{R}$30$^{\circ}$ and honeycomb superstructures near structurally defective armchair edges. Our results suggest that the honeycomb superstructure pattern results from superposition of two sets of ($\sqrt{3}\times\sqrt{3}$)$\textit{R}$30$^{\circ}$ superstructure with different phases. Our observation solves the mystery of the coexistence of two types of superstructures reported by prior studies.