Effect of Layer-Stacking on the Electronic Structure of Graphene Nanoribbons

TL;DR

This study uses ab initio DFT calculations to explore how stacking layers affects the electronic and magnetic properties of graphene nanoribbons, revealing layer-dependent band gaps and magnetic orderings.

Contribution

It provides new insights into the layer-dependent electronic structure and magnetic interactions in graphene nanoribbons, including the stability of magnetic states and quasiparticle corrections.

Findings

Multilayer armchair GNRs exhibit three classes of band gaps based on width.

Antiferromagnetic interlayer coupling is more stable than ferromagnetic.

Bilayer ZGNRs have a non-magnetic ground state with a small band gap.

Abstract

The evolution of electronic structure of graphene nanoribbons (GNRs) as a function of the number of layers stacked together is investigated using \textit{ab initio} density functional theory (DFT) including interlayer van der Waals interactions. Multilayer armchair GNRs (AGNRs), similar to single-layer AGNRs, exhibit three classes of band gaps depending on their width. In zigzag GNRs (ZGNRs), the geometry relaxation resulting from interlayer interactions plays a crucial role in determining the magnetic polarization and the band structure. The antiferromagnetic (AF) interlayer coupling is more stable compared to the ferromagnetic (FM) interlayer coupling. ZGNRs with the AF in-layer and AF interlayer coupling have a finite band gap while ZGNRs with the FM in-layer and AF interlayer coupling do not have a band gap. The ground state of the bi-layer ZGNR is non-magnetic with a small but finite band gap. The magnetic ordering is less stable in multilayer ZGNRs compared to single-layer ZGNRs. The quasipartcle GW corrections are smaller for bilayer GNRs compared to single-layer GNRs because of the reduced Coulomb effects in bilayer GNRs compared to single-layer GNRs.