Crystal Field Effect and Electric Field Screening in Multilayer Graphene with and without Twist

TL;DR

This study investigates the intrinsic polarization and electric field screening in multilayer graphene, revealing effects of crystal field and twist on polarization and dielectric properties using ab initio methods.

Contribution

It demonstrates the importance of crystal field effects in multilayer graphene and provides detailed parameters for modeling polarization and screening in these systems.

Findings

Multilayer graphene exhibits intrinsic polarization due to crystal field effects.

Twisted multilayer graphene shows stronger in-plane potential modulation.

Dielectric permittivity varies with electric field strength and configuration.

Abstract

We address the intrinsic polarisation and screening of external electric field in a broad range of ordered and twisted configurations of multilayer graphene, using an ab initio approach combining density functional theory and the Wannier function formalism. We show that multilayer graphene is intrinsically polarized due to the crystal field effect, an effect that is often neglected in tight-binding models of twisted bilayer graphene and similar systems. This intrinsic polarization of the order of up to few tens of meVs has different out-of-plane alignments in ordered and twisted graphene multilayers, while the in-plane potential modulation is found to be much stronger in twisted systems. We further investigate the dielectric permittivity $\varepsilon$ in same multilayer graphene configurations at different electric field strengths. Our findings establish a deep insight into intrinsic and extrinsic polarization in graphene multilayers and provide parameters necessary for building accurate models of these systems.