Quantum Transport in Chemically-modified Two-Dimensional Graphene: From Minimal Conductivity to Anderson Localization

TL;DR

This paper presents a computational study of charge transport in chemically-modified graphene, revealing how disorder affects conductivity and localization, with implications for understanding electronic properties of functionalized 2D materials.

Contribution

It introduces a combined tight-binding and real-space Kubo-Greenwood approach to analyze transport in disordered graphene, highlighting the transition from minimal conductivity to Anderson localization.

Findings

Identification of a minimum semi-classical conductivity in disordered graphene.

Observation of a crossover from weak to strong localization regimes.

Validation of a 2D Thouless relationship in a realistic disorder model.

Abstract

An efficient computational methodology is used to explore charge transport properties in chemically-modified (and randomly disordered) graphene-based materials. The Hamiltonians of various complex forms of graphene are constructed using tight-binding models enriched by first-principles calculations. These atomistic models are further implemented into a real-space order-N Kubo-Greenwood approach, giving access to the main transport length scales (mean free paths, localization lengths) as a function of defect density and charge carrier energy. An extensive investigation is performed for epoxide impurities with specific discussions on both the existence of a minimum semi-classical conductivity and a crossover between weak to strong localization regime. The 2D generalization of the Thouless relationship linking transport length scales is here illustrated based on a realistic disorder model.