Electronic transport through graphene nanoribbons with Stone-Wales reconstruction at edges and interfaces

TL;DR

This study investigates how Stone-Wales reconstruction at edges and interfaces affects the electronic conductance of graphene nanoribbons, revealing significant conductance suppression at certain voltages and specific transmission features.

Contribution

It provides a detailed analysis of the impact of Stone-Wales reconstruction on GNR conductance, including effects at edges and interfaces, using the transfer matrix method.

Findings

Edge reconstruction suppresses conductance at intermediate gate voltages.

Interface reconstruction reduces conductance across all gate voltages in armchair GNRs.

Transmission peaks at specific transverse momenta due to unit cell doubling.

Abstract

In this paper, we study the conductance of the graphene nanoribbons(GNRs) in the presence of the Stone-Wales(S-W) reconstruction, using the transfer matrix method. The ribbon is connected with semi-infinite quantum wires as the leads. The S-W reconstruction occurs on the edges and the interfaces between the electrodes and ribbon. When the reconstruction occurs on the edges, the conductance is suppressed considerably if the gate voltage $V_g$ takes intermediate values around $|V_{g}|\sim t_0$($t_0$ being the hopping amplitude of grahene) in both positive and negative energy regions. In contrast, if $V_g$ is close to the Dirac point or the band edges, the conductance is relatively insensitive to the edge reconstruction. The effect of edge reconstruction become less important with increasing ribbon width as expected. The S-W reconstruction occurs also possibly at the interfaces. In this case, the reconstruction suppresses identically the conductance in the entire range of $V_g$ for armchair GNRs. For the zigzag GNRs, the conductance is strongly suppressed in the negative energy region however the change of the conductance is relatively small in the positive energy region. We also analyze the transmission coefficients as functions of the channel index(the transverse momentum $k_y$ of the leads) for the neutral armchair GNRs with interface defects. Interestingly, there are two transmission peaks appearing at $k_{y}=\pi/3$ and $k_{y}=2\pi/3$ due to the unit cell doubling.