Sodium-terminated zigzag graphene nanoribbon: A one-dimensional semimetal with a tilted Dirac cone

TL;DR

This study uses first principles calculations to show that sodium-terminated zigzag graphene nanoribbons become one-dimensional tilted Dirac semimetals, revealing a new edge chemistry-induced electronic phase.

Contribution

It demonstrates that sodium termination at half the edge-carbon concentration induces a tilted Dirac cone in zigzag graphene nanoribbons, a novel electronic property.

Findings

Na-terminated ZGNR is a one-dimensional semimetal.

The Dirac cone in Na-ZGNR is tilted, unlike symmetric cones in pristine graphene.

Edge chemistry significantly alters electronic properties.

Abstract

Using first principles pseudopotential density functional theory calculations, we find that terminating zigzag graphene nanoribbons (ZGNR) with monovalent alkali atoms at a reduced concentration has a dramatic impact on their properties. In particular, using sodium atoms for the saturation of ZGNR edges at half the concentration of edge-carbon atoms make it a one dimensional, perfect semimetal, where the valance and conduction bands meet at only a single, Dirac-like point. Unlike pristine graphene, the Dirac-"cones" of Na-ZGNR is not symmetric with respect to wave vector, but rather it is tilted.