Charge-Transfer Plasmon Polaritons at Graphene/α-RuCl₃ Interfaces

Area of Science:

• Condensed Matter Physics
• Materials Science
• Nanotechnology

Background:

• Nanoscale charge control is crucial for plasmonics, band structure engineering, and topological properties of 2D materials.
• Exploiting material properties for intrinsic charge control is an ongoing research area.

Purpose of the Study:

• To visualize and quantify charge transfer at graphene/α-RuCl3 interfaces.
• To develop a novel method for nanoscale plasmonic interface generation without external doping or contacts.

Main Methods:

• Nanoimaging experiments on graphene/α-RuCl3 at ambient and cryogenic temperatures.
• Utilizing the electron affinity of α-RuCl3 to generate charge-transfer plasmon polaritons (CPPs).
• First-principles calculations to correlate plasmonic response with work function differences.

Main Results:

• Discovered robust plasmonic features in ungated and undoped graphene/α-RuCl3 structures.
• Quantified massive charge transfer via CPPs, enabling accurate Fermi energy measurement of graphene (EF = 0.6 eV).
• Linked the observed plasmonic response to the work function difference between graphene and α-RuCl3.

Conclusions:

• Charge-transfer plasmon polaritons (CPPs) provide a high-fidelity measure of graphene's Fermi energy.
• The work function difference between graphene and α-RuCl3 drives the formation of CPPs.
• This study presents a general strategy for creating nanometer-scale plasmonic interfaces intrinsically.