Impurities and electronic localization in graphene bilayers

TL;DR

This paper investigates how impurities affect electronic localization in bilayer graphene, especially under an electric field, revealing impurity-induced states that depend on field polarization and can cause Anderson localization.

Contribution

It provides a detailed analysis of impurity effects and localization phenomena in bilayer graphene with an applied electric field, highlighting the role of impurity states in electronic properties.

Findings

Impurities induce localized states within the field-induced gap.

Localization length varies with impurity distribution and electric field polarization.

Impurity states can partially fill the gap, affecting electronic transport.

Abstract

We analyze the electronic properties of bilayer graphene with Bernal stacking and a low concentration of adatoms. Assuming that the host bilayer lies on top of a substrate, we consider the case where impurities are adsorbed only on the upper layer. We describe non-magnetic impurities as a single orbital hybridized with carbon's pz states. The effect of impurity doping on the local density of states with and without a gated electric field perpendicular to the layers is analyzed. We look for Anderson localization in the different regimes and estimate the localization length. In the biased system, the field induced gap is partially filled by strongly localized impurity states. Interestingly, the structure, distribution and localization length of these states depend on the field polarization.