Charge-Transfer Plasmon Polaritons at Graphene/α-RuCl3Interfaces

Daniel J. Rizzo, Bjarke S. Jessen, Zhiyuan Sun, Francesco L. Ruta, Jin Zhang, Jia Qiang Yan, Lede Xian, Alexander S. McLeod, Michael E. Berkowitz, Kenji Watanabe, Takashi Taniguchi, Stephen E. Nagler, David G. Mandrus, Angel Rubio, Michael M. Fogler, Andrew J. Millis, James C. Hone, Cory R. Dean, D. N. Basov

Research output: Contribution to journalArticlepeer-review

63 Scopus citations

Abstract

Nanoscale charge control is a key enabling technology in plasmonics, electronic band structure engineering, and the topology of two-dimensional materials. By exploiting the large electron affinity of α-RuCl3, we are able to visualize and quantify massive charge transfer at graphene/α-RuCl3 interfaces through generation of charge-transfer plasmon polaritons (CPPs). We performed nanoimaging experiments on graphene/α-RuCl3 at both ambient and cryogenic temperatures and discovered robust plasmonic features in otherwise ungated and undoped structures. The CPP wavelength evaluated through several distinct imaging modalities offers a high-fidelity measure of the Fermi energy of the graphene layer: EF = 0.6 eV (n = 2.7 × 1013 cm-2). Our first-principles calculations link the plasmonic response to the work function difference between graphene and α-RuCl3 giving rise to CPPs. Our results provide a novel general strategy for generating nanometer-scale plasmonic interfaces without resorting to external contacts or chemical doping.

Original languageEnglish
Pages (from-to)8438-8445
Number of pages8
JournalNano Letters
Volume20
Issue number12
DOIs
StatePublished - Dec 9 2020

Keywords

  • Mott insulators
  • graphene
  • plasmon polaritons
  • scanning near-field optical microscopy (SNOM)
  • two-dimensional (2D) materials
  • α-RuCl

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