Coulomb disorder in three-dimensional Dirac systems

TL;DR

This paper develops a theory for Coulomb disorder in 3D Dirac materials, analyzing how long-range Coulomb interactions create electron/hole puddles, affect the disorder potential, and influence conductivity.

Contribution

It introduces a nonlinear screening theory for Coulomb disorder in 3D Dirac systems, providing quantitative estimates of disorder potential, puddle characteristics, and conductivity.

Findings

Disorder potential fluctuations are large due to Coulomb interactions.

Electron/hole puddles form with specific size and density.

Conductivity is affected by Coulomb disorder and puddle formation.

Abstract

In three-dimensional materials with a Dirac spectrum, weak short-ranged disorder is essentially irrelevant near the Dirac point. This is manifestly not the case for Coulomb disorder, where the long-ranged nature of the potential produced by charged impurities implies large fluctuations of the disorder potential even when impurities are sparse, and these fluctuations are screened by the formation of electron/hole puddles. In this paper I present a theory of such nonlinear screening of Coulomb disorder in three-dimensional Dirac systems, and I derive the typical magnitude of the disorder potential, the corresponding density of states, and the size and density of electron/hole puddles. The resulting conductivity is also discussed.