Ab initio quantum transport through armchair graphene nanoribbons: Streamlines in the current density

TL;DR

This study uses ab initio methods to analyze local current density in armchair graphene nanoribbons, revealing quantum confinement effects that produce distinct current streamlines and influence how adsorbates affect electronic transport.

Contribution

It provides the first detailed ab initio visualization of current streamlines in AGNRs, linking quantum confinement to current patterns and sensitivity to adsorbate placement.

Findings

Current streamlines exhibit threefold periodicity with ribbon width.

Adsorbates within current filaments cause strong backscattering.

Current patterns are highly sensitive to adsorbate placement.

Abstract

We calculate the local current density in pristine armchair graphene nanoribbons (AGNRs) with varying width, $N_\mathrm{C}$, employing a density-functional-theory-based ab initio transport formalism. We observe very pronounced current patterns (streamlines) with threefold periodicity in $N_\mathrm{C}$. They arise as a consequence of quantum confinement in the transverse flow direction. Neighboring streamlines are separated by stripes of almost vanishing flow. As a consequence, the response of the current to functionalizing adsorbates is very sensitive to their placement: adsorbates located within the current filaments lead to strong backscattering, while adsorbates placed in other regions have almost no impact at all.