Graphene/$\alpha$-RuCl$_3$: An Emergent 2D Plasmonic Interface

TL;DR

This study demonstrates a method to create highly-doped 2D plasmonic interfaces in graphene/$ ext{α}$-RuCl$_3$ heterostructures using charge transfer, enabling optical probing without electrostatic gating.

Contribution

It introduces a novel approach combining SNOM and DFT to characterize charge transfer and plasmonic behavior in 2D heterostructures, revealing significant doping effects.

Findings

Massive interlayer charge transfer of 2.7 × 10^{13} cm^{-2} observed.

Enhanced optical conductivity in $ ext{α}$-RuCl$_3$ due to doping.

Method enables probing of highly-doped plasmonic interfaces without electrostatic gates.

Abstract

Work function-mediated charge transfer in graphene/$\alpha$-RuCl$_3$ heterostructures has been proposed as a strategy for generating highly-doped 2D interfaces. In this geometry, graphene should become sufficiently doped to host surface and edge plasmon-polaritons (SPPs and EPPs, respectively). Characterization of the SPP and EPP behavior as a function of frequency and temperature can be used to simultaneously probe the magnitude of interlayer charge transfer while extracting the optical response of the interfacial doped $\alpha$-RuCl$_3$. We accomplish this using scanning near-field optical microscopy (SNOM) in conjunction with first-principles DFT calculations. This reveals massive interlayer charge transfer (2.7 $\times$ 10$^{13}$ cm$^{-2}$) and enhanced optical conductivity in $\alpha$-RuCl$_3$ as a result of significant electron doping. Our results provide a general strategy for generating highly-doped plasmonic interfaces in the 2D limit in a scanning probe-accessible geometry without need of an electrostatic gate.