SurfaceScience21 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 100: Mini-Symposium: Infrared nano-optics II
O 100.3: Vortrag
Donnerstag, 4. März 2021, 14:30–14:45, R2
Charge-transfer plasmon polaritons at graphene/α-RuCl3 interfaces — •Daniel J. Rizzo1, B.S. Jessen1, Z. Sun1, F.L. Ruta1, J. Zhang2, J.-Q. Yan3,4, L. Xian2, A.S. McLeod1, M.E. Berkowitz1, K. Watanabe5, T. Tanaguchi5, S.E. Nagler4, D.G. Mandrus3,4, A. Rubio2, M.M. Fogler6, A.J. Millis1, J.C. Hone1, C.R. Dean1, and D.N. Basov1 — 1Columbia University, New York, NY — 2Max Planck Institute, Hamburg, German — 3Univ. of Tennessee, Knoxville, TN — 4Oak Ridge National Laboratory, Oak Ridge, TN — 5NIMS, Japan — 6UCSD, San Diego, CA
Charge transfer at the interface of two atomically-thin layers with different work functions offers a means of tuning 2D charge densities without the inherent limitations of traditional electrostatic gates that possess thick gate insulators. Specifically, the large work function of the Mott insulator α-RuCl3 (6.1 eV) makes it an ideal 2D electron acceptor. In our study, we exploit this behavior to generate charge-transfer plasmon polaritons (CPPs) in graphene/α-RuCl3 heterostructures. Using near-field optical microscopy we measure the CPP dispersion, yielding a quantitative measure of the graphene Fermi energy (~0.6 eV) and thus the charge exchanged between α-RuCl3 and graphene (~2.7x10^13 cm-2). Concurrently, we observe dispersive edge modes and internal circular CPPs which reveal abrupt (<50 nm) changes in the graphene optical conductivity and charge density. Analysis of the CPP losses implies the presence of emergent optical conductivity in the doped interfacial layer of α-RuCl3. These results have broad implications for the study of highly-doped 2D materials.