Topological Aspects of Charge-Carrier Transmission across Grain Boundaries in Graphene

TL;DR

This study analyzes how topological defects at grain boundaries in graphene affect charge-carrier transmission, revealing suppression at low energies linked to localized states and back-scattering phenomena.

Contribution

It provides a systematic theoretical investigation of charge transport across grain boundaries in graphene, highlighting the role of topological defects and localized states in scattering.

Findings

Transmission is strongly suppressed at low energies with fewer dislocations.

Localized states of topological origin cause back-scattering.

Dislocations with certain Burgers vectors significantly impact charge transport.

Abstract

We systematically investigate the transmission of charge carriers across the grain-boundary defects in polycrystalline graphene by means of the Landauer-B\"uttiker formalism within the tight-binding approximation. Calculations reveal a strong suppression of transmission at low energies upon decreasing the density of dislocations with the smallest Burger's vector ${\mathbf b}=(1,0)$. The observed transport anomaly is explained from the point of view of back-scattering due to localized states of topological origin. These states are related to the gauge field associated with all dislocations characterized by ${\mathbf b}=(n,m)$ with $n-m \neq 3q$ ($q \in \mathbb{Z}$). Our work identifies an important source of charge-carrier scattering caused by topological defects present in large-area graphene samples produced by chemical vapor deposition.