Electrostatic Screening Modulation of Graphene's Electronic Structure and the Helical Wavefunction Dominated Topological Properties

TL;DR

This paper investigates how electrostatic screening influences graphene's electronic structure and topological properties using modified tight binding models, revealing band gap opening and helical wavefunction characteristics.

Contribution

It introduces a modified binding energy and bond charge model that accurately describes screening effects and topological features in graphene.

Findings

Exponential decay of the modified BBC potential suppresses electron interactions.

A band gap opens when model parameters exceed a threshold.

Low-energy helical wave functions exhibit topological characteristics.

Abstract

This study examines electrostatic screening effects in graphene using tight binding calculations based on the Binding energy and Bond Charge model and a modified version of it. The results indicate that the modified BBC potential decays in an exponential manner with distance, which suppresses electron electron interactions. The hopping integrals exhibit a pronounced decrease over distance and shift with parameter variation. A band gap opens once the parameter exceeds a certain threshold. The density of states shows a prominent peak near the Fermi level, whereas the low-energy region remains largely unchanged. The low energy helical wave functions in graphene display topological characteristics, including pseudospin momentum locking and a {\pi} Berry phase, resulting in distinctive transport properties. By avoiding the Coulomb singularity, the model offers valuable insights for the engineering of screening in two-dimensional systems and the design of topological devices.