First-principles study of the terahertz third-order nonlinear response of metallic armchair graphene nanoribbons

TL;DR

This study calculates the terahertz third-order nonlinear conductance of metallic armchair graphene nanoribbons, revealing significant enhancement over 2D graphene and dependence on Fermi level and temperature.

Contribution

It provides the first detailed theoretical analysis of third-order nonlinear responses in metallic armchair graphene nanoribbons using perturbation theory.

Findings

Enhanced third-order conductance compared to 2D graphene

Strong Fermi level dependence at low temperatures

Critical field strengths for nonlinear effects are between 1 and 5 kV/m

Abstract

We compute the terahertz third-order nonlinear conductance of metallic armchair graphene nanoribbons using time-dependent perturbation theory. Significant enhancement of the intrinsic third-order conductance over the result for instrinsic 2D single-layer graphene is observed over a wide range of temperatures. We also investigate the nonlinear response of extrinsic metallic acGNR with |E_F|<<200 meV. We find that the third-order conductance exhibits a strong Fermi level dependence at low temperatures. A third-order critical field strength of between 1 and 5 kV/m is computed for the Kerr conductance as a function of temperature. For the third-harmonic conductance, the minimum critical field is computed to be about about 5 kV/m.