Atomically localized plasmon enhancement in monolayer graphene

Abstract

Plasmons in graphene^1,2,3,4 can be tuned by using electrostatic gating or chemical doping^5,6,7, and the ability to confine plasmons in very small regions could have applications in optoelectronics^8,9, plasmonics^10,11 and transformation optics¹². However, little is known about how atomic-scale defects influence the plasmonic properties of graphene. Moreover, the smallest localized plasmon resonance observed in any material to date has been limited to around 10 nm (refs 13, 14, 15). Here, we show that surface plasmon resonances in graphene can be enhanced locally at the atomic scale. Using electron energy-loss spectrum imaging in an aberration-corrected scanning transmission electron microscope, we find that a single point defect can act as an atomic antenna in the petahertz (10¹⁵ Hz) frequency range, leading to surface plasmon resonances at the subnanometre scale.