Tunneling Plasmonics in Bilayer Graphene

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• 作者：Z. Fei ; E. G. Iwinski ; G. X. Ni ; L. M. Zhang ; W. Bao ; A. S. Rodin ; Y. Lee ; M. Wagner ; M. K. Liu ; S. Dai ; M. D. Goldflam ; M. Thiemens ; F. Keilmann ; C. N. Lau ; A. H. Castro-Neto ; M. M. Fogler ; D. N. Basov
• 刊名：Nano Letters
• 出版年：2015
• 出版时间：August 12, 2015
• 年：2015
• 卷：15
• 期：8
• 页码：4973-4978
• 全文大小：481K
• ISSN：1530-6992

文摘

We report experimental signatures of plasmonic effects due to electron tunneling between adjacent graphene layers. At subnanometer separation, such layers can form either a strongly coupled bilayer graphene with a Bernal stacking or a weakly coupled double-layer graphene with a random stacking order. Effects due to interlayer tunneling dominate in the former case but are negligible in the latter. We found through infrared nanoimaging that bilayer graphene supports plasmons with a higher degree of confinement compared to single- and double-layer graphene, a direct consequence of interlayer tunneling. Moreover, we were able to shut off plasmons in bilayer graphene through gating within a wide voltage range. Theoretical modeling indicates that such a plasmon-off region is directly linked to a gapped insulating state of bilayer graphene, yet another implication of interlayer tunneling. Our work uncovers essential plasmonic properties in bilayer graphene and suggests a possibility to achieve novel plasmonic functionalities in graphene few-layers.