Comparison of microscopic models for disorder in bilayer graphene: Implications for the density of states and the optical conductivity

TL;DR

This paper compares four microscopic models of disorder in bilayer graphene, analyzing their effects on the density of states and optical conductivity, and discusses implications for experimental gap measurements.

Contribution

It provides a direct comparison of different disorder models and approximations, highlighting their impact on electronic properties and experimental interpretations in bilayer graphene.

Findings

Qualitative similarity between scattering potentials

Self-energy approximation affects results near the band edge

Differences influence optical and transport gap measurements

Abstract

We study the effects of disorder on bilayer graphene using four different microscopic models and directly compare their results. We compute the self-energy, density of states, and optical conductivity in the presence of short-ranged scatterers and screened Coulomb impurities, using both the Born approximation and self-consistent Born approximation for the self-energy. We also include a finite interlayer potential asymmetry which generates a gap between the valence and conduction bands. We find that the qualitative behavior of the two scattering potentials are similar, but that the choice of approximation for the self-energy leads to important differences near the band edge in the gapped case. Finally, we describe how these differences manifest in the measurement of the band gap in optical and transport experimental techniques.