We present infrared transmission spectroscopy study of the inter-Landau-level excitations in quasi-neutral epitaxial graphene nanoribbon arrays. We observed a substantial deviation in energy of the L0(−1)→L1(0) transition from the characteristic square root magnetic-field dependence of two-dimensional graphene. This deviation arises from the formation of upper-hybrid mode between the Landau level transition and the plasmon resonance. In the quantum regime the hybrid mode exhibits a distinct dispersion relation, markedly different from that expected for conventional two-dimensional systems and highly doped graphene.
@article{arxiv.1305.4823,
title = {Magnetoplasmons in quasi-neutral epitaxial graphene nanoribbons},
author = {J. M. Poumirol and W. Yu and X. Chen and C. Berger and W. A. de Heer and M. L. Smith and T. Ohta and W. Pan and M. O. Goerbig and D. Smirnov and Z. Jiang},
journal= {arXiv preprint arXiv:1305.4823},
year = {2013}
}