Logarithm Diameter Scaling and Carrier Density Independence of One-Dimensional Luttinger Liquid Plasmon
Logarithm Diameter Scaling and Carrier Density Independence of One-Dimensional Luttinger Liquid Plasmon
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DOI：
10.1021/acs.nanolett.8b05031
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发表时间：
2019-04-01
期刊：
影响因子：
10.8
通讯作者：
Wang, Feng
中科院分区：
文献类型：
--
作者：
Wang, Sheng;Wu, Fanqi;Wang, Feng
一维（1D）金属中的量子限制电子由Luttinger液体描述。集体电荷激发（即，等离子体激元）在Luttinger液体中的行为可以与它们的常规对应物定性地不同。例如，Luttinger液体等离子体速度唯一地由电子-电子相互作用确定，其与1D材料的直径成比例。此外，预测Luttinger液体等离子体激元与载流子浓度无关。在这里，我们报告观察到这种不寻常的Luttinger液体等离子体激元行为的金属单壁碳纳米管，具有强电子量子限制的模型系统。我们利用红外纳米显微镜系统地研究了30多个不同直径的金属碳纳米管中的等离子体激元传播。我们建立了等离子体激元的速度有一个弱对数依赖于纳米管的直径，如预测的Luttinger液体理论。我们进一步研究了静电门控金属碳纳米管中的等离子体激元激发作为载流子密度的函数，并证明了等离子体激元速度完全独立于载流子密度。这些行为与一维金属壳层中的传统等离子体激元形成鲜明对比，在一维金属壳层中，等离子体激元色散随金属电子密度和一维直径急剧变化。Luttinger液体等离子体激元的不寻常行为可能使基于碳纳米管的新型纳米光子应用成为可能。
Quantum-confined electrons in one-dimensional (1D) metals are described by a Luttinger liquid. The collective charge excitations (i.e., plasmons) in a Luttinger liquid can behave qualitatively different from their conventional counterparts. For example, the Luttinger liquid plasmon velocity is uniquely determined by the electron-electron interaction, which scales logarithmly with the diameter of the 1D material. In addition, the Luttinger liquid plasmon is predicted to be independent of the carrier concentration. Here, we report the observation of such unusual Luttinger liquid plasmon behaviors in metallic single-walled carbon nanotubes, a model system featuring strong electron quantum confinement. We systematically investigate the plasmon propagation in over 30 metallic carbon nanotubes of different diameters using infrared nanoscopy. We establish that the plasmon velocity has a weak logarithm dependence on the nanotube diameter, as predicted by the Luttinger liquid theory. We further study the plasmon excitation as a function of the carrier density in electrostatically gated metallic carbon nanotubes and demonstrate that the plasmon velocity is completely independent of the carrier density. These behaviors are in striking contrast to conventional plasmons in 1D metallic shells, where the plasmon dispersion changes dramatically with the metal electron density and the 1D diameter. The unusual behaviors of Luttinger liquid plasmon may enable novel nanophotonic applications based on carbon nanotubes.