Negative high-harmonic differential conductivity in graphene nanoribbons

Abstract

We theoretically study current dynamics of graphene nanoribbons subject to bias 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 terahartz frequencies at even harmonics in graphene is suggested