The role of structural evolution on the quantum conductance behavior of gold nanowires during stretching

TL;DR

This study investigates how the structural changes in gold nanowires during stretching influence their quantum conductance, combining experiments and theoretical modeling to understand atomic arrangements and electronic transport.

Contribution

It provides a detailed analysis of the relationship between atomic structural evolution and conductance in gold nanowires, integrating experimental observations with theoretical calculations.

Findings

Gold nanowires adopt three main configurations during stretching.

Conductance correlates with specific atomic arrangements and configurations.

Carbon contamination reduces conductance in one-atom-thick wires.

Abstract

Gold nanowires generated by mechanical stretching have been shown to adopt only three kinds of configurations where their atomic arrangements adjust such that either the [100], [111] or [110] zone axes lie parallel to the elongation direction. We have analyzed the relationship between structural rearrangements and electronic transport behavior during the elongation of Au nanowires for each of the three possibilities. We have used two independent experiments to tackle this problem, high resolution transmission high resolution electron microscopy to observe the atomic structure and a mechanically controlled break junction to measure the transport properties. We have estimated the conductance of nanowires using a theoretical method based on the extended H\"uckel theory that takes into account the atom species and their positions. Aided by these calculations, we have consistently connected both sets of experimental results and modeled the evolution process of gold nanowires whose conductance lies within the first and third conductance quanta. We have also presented evidence that carbon acts as a contaminant, lowering the conductance of one-atom-thick wires.