Imaging the localization of the quasi-bound states in graphene antidots

TL;DR

This paper investigates charge transport in graphene with a central antidot, revealing how localized quasi-bound states influence conductance and how scanning probe techniques can identify their spatial localization.

Contribution

It introduces a method to determine the localization of quasi-bound states in graphene antidots using scanning probe techniques and analyzes how perturbations affect resonance properties.

Findings

Conductance peaks occur near narrow resonances of quasi-bound states.

Scanning probe can distinguish whether states are localized in the antidot or the entire cavity.

Perturbations shift resonance positions and modify their lifetimes.

Abstract

We consider charge transport across a finite graphene flake with a circular antidot defined in its center. The flake is connected to thin metallic armchair nanoribbons and the study covers the energy range within the neighborhood of the neutrality point. We solve the scattering problem using the tight-binding Hamiltonian and find that conductance of the system is non-zero only near narrow resonances which are quasi-bound in either the entire cavity or the antidot itself. We demonstrate that the scanning probe technique can be used for the purpose of determination whether the state is localized within the antidot or in the entire cavity. We indicate that the potential of the perturbation shifts the position of the resonances and that the shifts are related to the localization of the scattering probability density. The resonance lifetime can be both decreased or increased as the perturbation introduced by the probe interferes with the current vortices inside the antidot.