Abstract
We point out that plasmons in doped graphene simultaneously enable low losses and significant wave localization for frequencies below that of the optical phonon branch . Large plasmon losses occur in the interband regime (via excitation of electron-hole pairs), which can be pushed toward higher frequencies for higher-doping values. For sufficiently large dopings, there is a bandwidth of frequencies from up to the interband threshold, where a plasmon decay channel via emission of an optical phonon together with an electron-hole pair is nonegligible. The calculation of losses is performed within the framework of a random-phase approximation and number conserving relaxation-time approximation. The measured DC relaxation-time serves as an input parameter characterizing collisions with impurities, whereas the contribution from optical phonons is estimated from the influence of the electron-phonon coupling on the optical conductivity. Optical properties of plasmons in graphene are in many relevant aspects similar to optical properties of surface plasmons propagating on dielectric-metal interface, which have been drawing a lot of interest lately because of their importance for nanophotonics. Therefore, the fact that plasmons in graphene could have low losses for certain frequencies makes them potentially interesting for nanophotonic applications.
- Received 30 September 2009
DOI:https://doi.org/10.1103/PhysRevB.80.245435
©2009 American Physical Society
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Physical Review B 50th Anniversary Milestones
These Milestone studies represent lasting contributions to physics by way of reporting significant discoveries, initiating new areas of research, or substantially enhancing the conceptual tools for making progress in the burgeoning field of condensed matter physics.