Appearance of Negative Differential Conductivity in Graphene Nanoribbons at High-Harmonics

TL;DR

This paper theoretically investigates the current response of graphene nanoribbons under combined dc and ac fields, revealing negative high-harmonic differential conductivity and potential for terahertz frequency generation.

Contribution

It demonstrates the emergence of negative differential conductivity at high harmonics in graphene nanoribbons under specific bias conditions, highlighting novel nonlinear electronic behaviors.

Findings

Negative high-harmonic differential conductivity observed.

Both even and odd harmonic negative differential conductivities identified.

Potential application in terahertz frequency generation suggested.

Abstract

We theoretically study current dynamics of graphene nanoribbons subject to bias dc and ac driven fields. We showed that graphene nanoribbons exhibit negative high-harmonic differential conductivity. Negative differential conductivity appears when bias electric filed is in the neighborhood of applied ac filed amplitude. We also observe both even and odd high-harmonic negative differential conductivity at wave mixing of two commensurate frequencies. The even harmonics are more pronounced than the odd harmonics. A possible use of the present method for generating terahertz frequencies at even harmonics in graphene is suggested.