High-energy plasmon spectroscopy of freestanding multilayer graphene

TL;DR

This paper models high-energy plasmon spectra in freestanding multilayer graphene using a layered electron gas approach, explaining experimental observations and clarifying the nature of plasmon modes in these structures.

Contribution

It introduces an analytical layered electron gas model with a two-fluid polarizability to analyze plasmon spectra in multilayer graphene, aligning well with experimental data.

Findings

Good agreement with experimental plasmon spectra for N<10

Clarification of the role of bulk versus surface plasmons

Insights into plasmon dispersion and mode interference

Abstract

We present several applications of the layered electron gas model to electron energy loss spectroscopy of free-standing films consisting of $N$ graphene layers in a scanning transmission electron microscope. Using a two-fluid model for the single-layer polarizability, we discuss the evolution of high-energy plasmon spectra with $N$, and find good agreement with the recent experimental data for both multi-layer graphene with $N<10$, and thick slabs of graphite. Such applications of these analytical models help shed light on several features observed in the plasmon spectra of those structures, including the role of plasmon dispersion, dynamic interference in excitations of various plasmon eigenmodes, as well as the relevance of the bulk plasmon bands, rather than surface plasmons, in classifying the plasmon peaks.