Predicting edge-localized monovacancy defects in zigzag graphene nanoribbons from Floquet quasienergy spectrum

TL;DR

This paper presents a theoretical method using Floquet-Bloch formalism to predict the location of monovacancy defects at the edges of zigzag graphene nanoribbons by analyzing their quasienergy spectrum under polarized light, aiding defect detection.

Contribution

The study introduces a novel Floquet-based framework for predicting edge defects in ZGNRs from quasienergy spectra, applicable to various vacancy types.

Findings

Circularly polarized light reveals defect locations via Floquet edge states.

Appearance of new Dirac points correlates with defect positions.

Method aligns with experimental tr-ARPES observations.

Abstract

In this work, we prescribe a theoretical framework aiming at predicting the position of monovacancy defects at the edges of zigzag graphene nanoribbons (ZGNRs) using Floquet-Bloch formalism, which can be experimentally observed through time- and angle-resolved photoemission spectroscopy (tr-ARPES). Our methodology involves an in-depth investigation of the Floquet quasienergy band spectrum influenced by light with varying polarization across a range of frequencies. Particularly under the influence of circularly polarized light with a frequency comparable to the bandwidth of the system, our findings suggest a promising approach for locating monovacancy defects at either edge, a challenge that proves intricate to predict from the ARPES spectrum of ZGNRs with monovacancy defects. This has been achieved by analyzing the orientation of the Floquet edge state and the appearance of new Dirac points in the vicinity of the Fermi level. The real-world applications of these captivating characteristics underscore the importance and pertinence of our theoretical framework, paving the way for additional exploration and practical use. Our approach, employing the Floquet formalism, is not limited to monovacancy-type defects; rather, it can be expanded to encompass various types of vacancy defects.