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Outline Damping mechanisms l Plasmons in ribbons Experimental results

Momentum dependence and losses in graphene plasmons. Graphene Nanophotonics Benasque , 2013, Mar 03 -- Mar 08. Outline Damping mechanisms l Plasmons in ribbons Experimental results. Mid-infrared plasmons in scaled graphene nanostructures

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Outline Damping mechanisms l Plasmons in ribbons Experimental results

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  1. Momentumdependence and losses in grapheneplasmons GrapheneNanophotonics Benasque, 2013, Mar 03 -- Mar 08 • Outline • Dampingmechanisms l Plasmons in ribbons • Experimental results Mid-infraredplasmons in scaledgraphenenanostructures H. Yan, T. Low, W. Zhu, Y. Wu, M. Freitag, X. Li, F. G., P. Avouris, F. Xia arXiv:1209.1984, NaturePhotonics, in press L. Martín-Moreno, A. Nikitin, F. García-Vidal, M. M. Fogler

  2. Dampingmechanisms • l Higherorderprocesses, multipleelectron-holepairs • Lack of momentumconservation • l Decayintootherexcitations: phonons, …

  3. Elasticscattering k’ k elastic mean free path k+q

  4. Finitesystems D

  5. Inhomogeneouselectricfields T. Low, M. M. Fogler, F. G, unpublished Edges Local excitations wp(q) 4 q 4 L-1

  6. Inhomogeneouselectricfields Non local conductivity, cleansystem t=1ms, E =0.4eV F

  7. Surface polar modes Si O has polar modeswhich induce longrangeelectrostaticpotentials. Thedielectricconstant of thesystemismodified. 2

  8. Opticalphonons q k’ k k+q Opticalphonons at G, w =0.2 eV ph Couplingthroughchanges in bond lengths Weakdispersion 1/t e

  9. Experiments Y. Yan, T. Low, W. Zhu,Y. Wu, M. Freitag, X. Li, F. G., P. Avouris, and F. Xia, arXiv:1209.1984, NaturePhys., in press Nanoribbons, antidots , and nanodisksdefinedbyelectronbeamlitography. Thesamples lie on CVD grapheneonSiO and diamondlikecarbon (DLC) substrates. 2

  10. Plasmondispersion grapheneondiamondlikecarbon (DLC) deadlayer asymmetriclineshape

  11. Plasmondispersion grapheneonSiO 2

  12. Plasmondamping

  13. Plasmondamping ComparisonbetweengrapheneonSiO and grapheneon DLC 2 Doping dependence

  14. Conclusions. Open questions • l Plasmondispersion can beaccuratelymeasured in nanoribbons. • Plasmonlinewidth can beexplainedby simple mechanisms • Themaindecaychannel at highfrequenciesisdecayintoopticalphonons and electron-holepairs • The role of otherdecaychannelsis in reasonableagreementwith simple estimates • l Coulomb blockade, interplaybetweenplasmons and dctransport

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