Gate-tunable plasmons in mixed-dimensional van der Waals heterostructures

Sheng Wang,Takashi Taniguchi,Chongwu Zhou,Zuocheng Zhang,Salman Kahn,Hongyuan Li,Sihan Zhao,Seokjae Yoo,Dingzhou Cui,Danqing Wang,Lili Jiang,M Iqbal Bakti Utama,Feng Wang,Wenyu Zhao,Shaowei Li,Emma Regan,Kenji Watanabe,Alexander Zibrov,Fanqi Wu

doi:10.1038/s41467-021-25269-0

Abstract

Surface plasmons, collective electromagnetic excitations coupled to conduction electron oscillations, enable the manipulation of light–matter interactions at the nanoscale. Plasmon dispersion of metallic structures depends sensitively on their dimensionality and has been intensively studied for fundamental physics as well as applied technologies. Here, we report possible evidence for gate-tunable hybrid plasmons from the dimensionally mixed coupling between one-dimensional (1D) carbon nanotubes and two-dimensional (2D) graphene. In contrast to the carrier density-independent 1D Luttinger liquid plasmons in bare metallic carbon nanotubes, plasmon wavelengths in the 1D-2D heterostructure are modulated by 75% via electrostatic gating while retaining the high figures of merit of 1D plasmons. We propose a theoretical model to describe the electromagnetic interaction between plasmons in nanotubes and graphene, suggesting plasmon hybridization as a possible origin for the observed large plasmon modulation. The mixed-dimensional plasmonic heterostructures may enable diverse designs of tunable plasmonic nanodevices.

Highlights

Surface plasmons, collective electromagnetic excitations coupled to conduction electron oscillations, enable the manipulation of light–matter interactions at the nanoscale
Ultraclean single-walled carbon nanotubes (SWNTs) are directly grown onto SiO2/Si substrates by chemical vapor deposition (CVD)[8,9]
SWNT/hexagonal boron nitride (h-BN)/Graphene heterostructures are assembled by the standard polymer stamp dry-transfer technique[28]

Summary

Introduction

Collective electromagnetic excitations coupled to conduction electron oscillations, enable the manipulation of light–matter interactions at the nanoscale. We report possible evidence for gate-tunable hybrid plasmons from the dimensionally mixed coupling between one-dimensional (1D) carbon nanotubes and two-dimensional (2D) graphene. We report experimental and theoretical studies of plasmons in mixed-dimensional SWNT/h-BN/graphene heterostructures, which serve as an exemplary 1D-2D hybrid plasmonic system. The results indicate that the experimentally observed tunable plasmon modes are most likely to be interpreted as hybrid plasmons due to the coupling between the 1D SWNT plasmons and the 2D graphene plasmons. This coupling is theoretically expected to lead to efficient electrical control of the highly localized plasmon excitations along the nanotube. The approach can be used to design hybrid plasmonic devices with varying functionalities

Methods

Results

Conclusion