Screening in multilayer graphene

TL;DR

This paper derives analytical expressions for the static polarization in ABC-stacked multilayer graphene, focusing on trilayer systems, to better understand screening effects relevant for electronic properties.

Contribution

It provides the first analytical integral expressions for polarization in ABC-stacked multilayer graphene, including a universal low-momentum result and a high-momentum linear approximation.

Findings

The low-momentum polarization is universal and doping-independent.

The high-momentum polarization slope is three times that of monolayer graphene.

Results enable improved modeling of screening effects in multilayer graphene systems.

Abstract

In this article we study the static polarization in ABC-stacked multilayer graphene. Since the density of states diverges for these systems if the number of layers exceeds three, screening effects are expected to be important. In the random phase approximation, screening can be included through the polarization. We derive an analytical integral expression for the polarization in both the full-band model and an effective two-band model. Numerical evaluation of these integrals are very time consuming in the full-band model. Hence, for ABC-stacked trilayer graphene, we use the two-band model to calculate the low momentum part of the polarization. The results for the two-band model are universal, i.e. independent of doping. The high momentum part is linear and is determined by calculating two points, such that we can determine the slope. For ABC stacked trilayer graphene, the slope is given by three times the monolayer value. We compare our results to previous ones in the literature and discuss the similarities and discrepancies. Our results can be used to include screening in ABC-stacked multilayer systems in a way that all the characteristics of the polarization function are included. The numerical results for the polarization of trilayer graphene are used to sketch the screened potential.