Engineering Robust Metallic Zero-Mode States in Olympicene Graphene Nanoribbons

TL;DR

This paper demonstrates the design and synthesis of metallic graphene nanoribbons with robust zero-mode states, combining theoretical predictions and experimental validation to advance low-dimensional electronic materials.

Contribution

It introduces a regioregular synthesis method for olympicene GNRs with embedded zero-mode superlattices, enabling stable metallic states not previously achieved.

Findings

Theoretical models predict dispersive metallic bands from zero-mode interactions.

DFT calculations confirm the presence of robust metallic zero-mode bands.

Experimental STM spectroscopy validates the metallic states in synthesized GNRs.

Abstract

Metallic graphene nanoribbons (GNRs) represent a critical component in the toolbox of low-dimensional functional materials technolo-gy serving as 1D interconnects capable of both electronic and quantum information transport. The structural constraints imposed by on-surface bottom-up GNR synthesis protocols along with the limited control over orientation and sequence of asymmetric monomer building blocks during the radical step-growth polymerization has plagued the design and assembly of metallic GNRs. Here we report the regioregular synthesis of GNRs hosting robust metallic states by embedding a symmetric zero-mode superlattice along the backbone of a GNR. Tight-binding electronic structure models predict a strong nearest-neighbor electron hopping interaction between adjacent zero-mode states resulting in a dispersive metallic band. First principles DFT-LDA calculations confirm this prediction and the robust, metallic zero-mode band of olympicene GNRs (oGNRs) is experimentally corroborated by scanning tunneling spectroscopy.