Rizzo Daniel J, Jessen Bjarke S, Sun Zhiyuan, Ruta Francesco L, Zhang Jin, Yan Jia-Qiang, Xian Lede, McLeod Alexander S, Berkowitz Michael E, Watanabe Kenji, Taniguchi Takashi, Nagler Stephen E, Mandrus David G, Rubio Angel, Fogler Michael M, Millis Andrew J, Hone James C, Dean Cory R, Basov D N
Department of Physics, Columbia University, New York, New York 10027, United States.
Department of Mechanical Engineering, Columbia University, New York, New York 10027, United States.
Nano Lett. 2020 Dec 9;20(12):8438-8445. doi: 10.1021/acs.nanolett.0c03466. Epub 2020 Nov 9.
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-RuCl, we are able to visualize and quantify massive charge transfer at graphene/α-RuCl interfaces through generation of charge-transfer plasmon polaritons (CPPs). We performed nanoimaging experiments on graphene/α-RuCl 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: = 0.6 eV ( = 2.7 × 10 cm). Our first-principles calculations link the plasmonic response to the work function difference between graphene and α-RuCl 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.
纳米级电荷控制是等离子体激元学、电子能带结构工程和二维材料拓扑学中的一项关键使能技术。通过利用α-RuCl的大电子亲和性，我们能够通过产生电荷转移等离子体激元（CPP）来可视化和量化石墨烯/α-RuCl界面处的大量电荷转移。我们在环境温度和低温下对石墨烯/α-RuCl进行了纳米成像实验，并在其他未栅控和未掺杂的结构中发现了稳健的等离子体激元特征。通过几种不同的成像方式评估的CPP波长提供了对石墨烯层费米能量的高保真测量：λ = 0.6 eV（k = 2.7 × 10 cm）。我们的第一性原理计算将等离子体激元响应与石墨烯和α-RuCl之间的功函数差联系起来，从而产生了CPP。我们的结果提供了一种新颖的通用策略，无需借助外部接触或化学掺杂即可生成纳米级等离子体激元界面。
