Numerical study of the lattice vacancy effects on the single-channel electron transport of graphite ribbons

TL;DR

This study uses a tight binding model and Landauer approach to analyze how lattice vacancies affect the electron conductance in nanographite ribbons, revealing dependence on vacancy type and edge states.

Contribution

It provides new insights into the impact of lattice vacancies on conductance, especially the role of sublattice imbalance and edge states in nanographite ribbons.

Findings

Large vacancies with sublattice imbalance cause zero-conductance dips.

Vacancies with balanced sublattices do not produce dips.

Conductance behavior relates to the Longuet-Higgins conjecture.

Abstract

Lattice vacancy effects on electrical conductance of nanographite ribbon are investigated by means of the Landauer approach using a tight binding model. In the low-energy regime ribbons with zigzag boundary provide a single conducting channel whose origin is connected with the presence of edge states. It is found that the chemical potential dependence of conductance strongly depends on the difference ($\Delta$) of the number of removed A and B sublattice sites. The large lattice vacancy with $\Delta\neq 0$ shows $2\Delta$ zero-conductance dips in the single-channel region, however, the large lattice vacancy with $\Delta=0$ has no dip structure in this region. The connection between this conductance rule and the Longuet-Higgins conjecture is also discussed.