Effect of Temperature and Doping on Plasmon Excitations for an Encapsulated Double-Layer Graphene Heterostructure

TL;DR

This paper presents a theoretical analysis of how temperature and doping affect plasmon excitations in encapsulated double-layer graphene, revealing tunable plasmon modes for nanoscale light manipulation.

Contribution

It introduces a formalism based on surface response functions to analyze plasmon spectra in encapsulated graphene heterostructures, including effects of temperature and doping.

Findings

Identification of linear acoustic and low-frequency in-phase plasmon modes

Demonstration of tunability of plasmon spectra via doping and temperature

Relevance to energy transfer in graphene-based nanostructures

Abstract

We perform a comprehensive analysis of the spectrum of graphene plasmons which arise when a pair of sheets are confined between conducting materials. The associated enhanced local fields may be employed in the manipulation of light on the nanoscale by adjusting the separation between the graphene layers, the energy band gap as well as the concentration of charge carriers in the conducting media surrounding the two-dimensional (2D) layers. We present a theoretical formalism, based on the calculation of the surface response function, for determining the plasmon spectrum of an encapsulated pair of 2D layers and apply it to graphene. We solve the coupled equations involving the continuity of the electric potential and discontinuity of the electric field at the interfaces separating the constituents of the hybrid structure. We have compared the plasmon modes for encapsulated gapped and gapless graphene. The associated nonlocal graphene plasmon spectrum coupled to the "sandwich" system show a linear acoustic plasmon mode as well as a low-frequency mode corresponding to in-phase oscillations of the adjacent 2D charge densities. These calculations are relevant to the study of energy transfer via plasmon excitations when graphene is confined by a pair of thick conducting materials.