Controlled Growth of a Line Defect in Graphene and Implications for Gate-Tunable Valley Filtering

TL;DR

This paper presents a method for creating precise 5-5-8 line defects in graphene using electron irradiation and Joule heating, demonstrating their potential for valley filtering and valleytronics applications.

Contribution

It introduces a controlled fabrication technique for graphene line defects and explores their valley filtering capabilities through first-principles calculations.

Findings

Successful fabrication of regular 5-5-8 line defects in graphene.

Strong energy-dependent valley polarization across the defect.

Proposal of a valley valve device for valleytronics.

Abstract

Atomically precise tailoring of graphene can enable unusual transport pathways and new nanometer-scale functional devices. Here we describe a recipe for the controlled production of highly regular "5-5-8" line defects in graphene by means of simultaneous electron irradiation and Joule heating by applied electric current. High-resolution transmission electron microscopy reveals individual steps of the growth process. Extending earlier theoretical work suggesting valley-discriminating capabilities of a graphene 5-5-8 line defect, we perform first-principles calculations of transport and find a strong energy dependence of valley polarization of the charge carriers across the defect. These findings inspire us to propose a compact electrostatically gated "valley valve" device, a critical component for valleytronics.