Interactions and screening in gated bilayer graphene nanoribbons

TL;DR

This paper investigates how Coulomb interactions and screening influence the electronic properties of gated bilayer graphene nanoribbons, revealing edge accumulation effects and a nonmonotonous energy gap behavior.

Contribution

It provides a self-consistent theoretical analysis of Coulomb interaction effects on gated BGNs, highlighting edge accumulation and energy gap collapse phenomena.

Findings

Electrons accumulate at nanoribbon edges due to interactions.

The energy gap varies nonmonotonously with gate voltage.

Energy dispersion warping is induced by interactions.

Abstract

The effects of Coulomb interactions on the electronic properties of bilayer graphene nanoribbons (BGNs) covered by a gate electrode are studied theoretically. The electron density distribution and the potential profile are calculated self-consistently within the Hartree approximation. A comparison to their single-particle counterparts reveals the effects of interactions and screening. Due to the finite width of the nanoribbon in combination with electronic repulsion, the gate-induced electrons tend to accumulate along the BGN edges where the potential assumes a sharp triangular shape. This has a profound effect on the energy gap between electron and hole bands, which depends nonmonotonously on the gate voltage and collapses at intermediate electric fields. We interpret this behavior in terms of interaction-induced warping of the energy dispersion.