Regular quantum plasmons in segments of graphene nanoribbons

Abstract

Graphene plasmons have advantages over noble metal plasmons such as high tunability and low loss. However, for graphene nanostructures smaller than 10 nm, little is known about their plasmons or whether regular plasmonic behavior exists, despite their potential applications. Here, we present first-principles calculations of plasmon excitations in zigzag graphene nanoribbon segments. Very regular plasmonic behavior is found: Only one plasmon mode exists in the low-energy regime ([Formula: see text] eV). The classical electrostatic scaling law still approximately holds when the width ([Formula: see text]) is larger than [Formula: see text] nm but totally fails when [Formula: see text] nm due to quantum effects. The scaling with different doping densities shows that the plasmon is nearly free-electron plasmon instead of Dirac plasmon.