Disorder Effects on the Quasiparticle and Transport Properties of Two-Dimensional Dirac Fermionic Systems

TL;DR

This study uses a nonperturbative numerical approach to analyze how disorder affects quasiparticle and transport properties in two-dimensional Dirac systems like graphene, revealing significant modifications even with weak disorder.

Contribution

It provides a comprehensive numerical analysis of disorder effects on Dirac fermions, including fractional power-law energy dependences and the impact of different disorder types.

Findings

Quasiparticle residues vanish at the Dirac point due to disorder.

Power-law energy dependences of self-energy with fractional exponents.

Disorder effects are consistent across various impurity correlation types.

Abstract

Despite extensive existing studies, a complete understanding of the role of disorder in affecting the physical properties of two-dimensional Dirac fermionic systems remains a standing challenge, largely due to obstacles encountered in treating multiple scattering events for such inherently strong scattering systems. Using graphene as an example and a nonperturbative numerical technique, here we reveal that the low energy quasiparticle properties are considerably modified by multiple scattering processes even in the presence of weak scalar potentials. We extract unified power-law energy dependences of the self-energy with fractional exponents from the weak scattering limit to the strong scattering limit from our numerical analysis, leading to sharp reductions of the quasiparticle residues near the Dirac point, eventually vanishing at the Dirac point. The central findings stay valid when the Anderson-type impurities are replaced by correlated Gaussian- or Yukawa-type disorder with varying correlation lengths. The improved understanding gained here also enables us to provide better interpretations of the experimental observations surrounding the temperature and carrier density dependences of the conductivity in ultra-high mobility graphene samples. The approach demonstrated here is expected to find broad applicability in understanding the role of various other types of impurities in two-dimensional Dirac systems.