Inducing Metallicity in Graphene Nanoribbons via Zero-Mode Superlattices

TL;DR

This paper presents a novel method to induce and control metallic states in graphene nanoribbons by inserting zero-energy mode superlattices, verified through experiments and theoretical calculations.

Contribution

It introduces a general technique for inducing metallicity in GNRs using zero-mode superlattices, enabling tunable electronic properties.

Findings

Metallicity in GNRs can be achieved with zero-mode superlattices.

Metallic bandwidth is tunable via zero-mode wavefunction overlap.

Experimental and theoretical methods confirm the induced metallic states.

Abstract

The design and fabrication of robust metallic states in graphene nanoribbons (GNRs) is a significant challenge since lateral quantum confinement and many-electron interactions tend to induce electronic band gaps when graphene is patterned at nanometer length scales. Recent developments in bottom-up synthesis have enabled the design and characterization of atomically-precise GNRs, but strategies for realizing GNR metallicity have been elusive. Here we demonstrate a general technique for inducing metallicity in GNRs by inserting a symmetric superlattice of zero-energy modes into otherwise semiconducting GNRs. We verify the resulting metallicity using scanning tunneling spectroscopy as well as first-principles density-functional theory and tight binding calculations. Our results reveal that the metallic bandwidth in GNRs can be tuned over a wide range by controlling the overlap of zero-mode wavefunctions through intentional sublattice symmetry-breaking.