Nodal adsorbate bound states in armchair graphene nanoribbons: Fano resonances and adsorbate recognition in weak disorder

Abstract

We consider adsorbates on metallic armchair-graphene nanoribbons (AGNRs). An adsorbed atom on a nodal site of the gapless subband in the AGNR is found to induce a bound state. The nodal-adsorbate bound state alone does not cause reflection in the AGNR quantum transport in the one propagating-channel regime. Yet its manifestation, as a Fano resonance in G, is brought forth by the presence of a non-nodal adsorbate (or a scatterer) located on a longitudinally separated site. Both the adsorbate-dependent nature and the significantly enhanced energy resolution of the Fano structure in G invite adsorbate recognition. The Fano peak is shown to be robust against weak disorder such as from edge vacancies, due to the localized nature of the Fano resonant state. Adsorbates F and OH, described within an extended Hückel model, are considered as examples.

Conductance of disordered graphene sheets: A real space approach

“…In Figs 6-7 (a) and Figs 6-7 (b) around 7-8 eV some localized states are formed for graphene lattice with random SW defects with and without rippling respectively. These resonant states can be associated with the Fano resonance [82][83][84] which occur when one or more discrete levels (the resonant process) interact with a continuum of states (the background process). Near the resonant energy, the scattering amplitude from background varies slowly with energy while the resonant scattering amplitude changes magnitude and phase quickly.…”