Exotic plasmon modes of double layer graphene

TL;DR

This paper derives and analyzes the unique plasmon dispersion relations in doped double layer graphene, revealing exotic properties influenced by layer doping and separation, distinct from traditional 2D electron systems.

Contribution

It provides the first detailed theoretical derivation of plasmon modes in double layer graphene, highlighting unexpected effects of doping and inter-layer separation.

Findings

Nontrivial influence of an undoped layer on plasmon dispersion

Strange effects of the second layer even at weak coupling

Distinct plasmon properties compared to parabolic 2D systems

Abstract

We derive the plasmon dispersion in doped double layer graphene (DLG), made of two parallel graphene mono-layers with carrier densities $n_1$ and $n_2$ respectively, and an inter-layer separation of $d$. The linear chiral gapless single particle energy dispersion of graphene leads to exotic DLG plasmon properties with several unexpected experimentally observable characteristic features such as a nontrivial influence of an undoped ($n_2=0$) layer on the DLG plasmon dispersion and a strange influence of the second layer even in the weak-coupling $d\to 0$ limit. Our predicted exotic DLG plasmon properties clearly distinguish graphene from the extensively studied usual parabolic 2D electron systems.