Year: 2013
Type: article
Abstract: We consider theoretically, using the random phase approximation (RPA), low-energy intrinsic plasmons for two-dimensional (2D) systems obeying Dirac-like linear chiral dispersion with the chemical potential set precisely at the charge neutral Dirac point. The ``intrinsic Dirac plasmon'' energy has the characteristic $\sqrt{q}$ dispersion in the 2D wave vector $q$, but vanishes as $\sqrt{T}$ in temperature for both monolayer and bilayer graphene. The intrinsic plasmon becomes overdamped for a fixed $q$ as $T\ensuremath{\rightarrow}0$ since the level broadening (i.e., the decay of the plasmon into electron-hole pairs due to Landau damping) increases as $1/\sqrt{T}$ as temperature decreases, however, the plasmon mode remains well defined at any fixed $T$ (no matter how small) as $q\ensuremath{\rightarrow}0$. We find the intrinsic plasmon to be well defined as long as $q<\frac{{k}_{B}T}{{e}^{2}}$. We give analytical results for low and high temperatures, and numerical RPA results for arbitrary temperatures, and consider both single- and double-layer intrinsic Dirac plasmons. We provide extensive comparison and contrast between intrinsic and extrinsic graphene plasmons, and critically discuss the prospects for experimentally observing intrinsic Dirac point graphene plasmons.
Source: Physical Review B
Authors: S. Das Sarma, Qiuzi Li
Institution: University of Maryland, College Park
Language: English
Subfield: Biomedical Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W136935401