STM observation of the quantum interference effect in finite-sized graphite

TL;DR

This study uses STM to observe quantum interference patterns in finite-sized graphene sheets, revealing how electron wave interference influences surface patterns and local density of states.

Contribution

It demonstrates the observation of quantum interference effects in finite-sized graphene using STM, highlighting the influence of electron wave confinement and bias voltage on surface patterns.

Findings

Interference patterns depend on electron wave confinement.

Pattern periodicity varies with inclination and bias voltage.

Local density of states shows spatial variation due to interference.

Abstract

Superperiodic patterns were observed by STM on two kinds of finite-sized graphene sheets. One is nanographene sheets inclined from a highly oriented pyrolitic graphite (HOPG) substrate and the other is several-layer-thick graphene sheets with dislocation-network structures against a HOPG substrate. As for the former, the in-plane periodicity increased gradually in the direction of inclination, and it is easily changed by attachment of a nanographite flake on the nanographene sheets. The oscillation pattern can be explained by the interference of electron waves confined in the inclined nanographene sheets. As for the latter, patterns and their corrugation amplitudes depended on the bias voltage and on the terrace height from the HOPG substrate. The interference effect by the perturbed and unperturbed waves in the overlayer is responsible for the patterns whose local density of states varies in space.