We report on infrared (IR) nanoscopy of 2D plasmon excitations of Dirac fermions in graphene. This is achieved by confining mid-IR radiation at the apex of a nanoscale tip: an approach yielding two orders of magnitude increase in the value of in-plane component of incident wavevector q compared to free space propagation. At these high wavevectors, the Dirac plasmon is found to dramatically enhance the near-field interaction with mid-IR surface phonons of SiO2 substrate. Our data augmented by detailed modeling establish graphene as a new medium supporting plasmonic effects that can be controlled by gate voltage.
@article{arxiv.1112.0390,
title = {Infrared nanoscopy of Dirac plasmons at the graphene-SiO2 interface},
author = {Zhe Fei and Gregory O. Andreev and Wenzhong Bao and Lingfeng M. Zhang and Alexander S. McLeod and Chen Wang and Magaret K. Stewart and Zeng Zhao and Gerardo Dominguez and Mark Thiemens and Michael M. Fogler and Michael J. Tauber and Antonio H. Castro-Neto and Chun Ning Lau and Fritz Keilmann and Dimitri N. Basov},
journal= {arXiv preprint arXiv:1112.0390},
year = {2011}
}