Resistive and rectifying effects of pulling gold atoms at thiol-gold nano-contacts

TL;DR

This study uses first-principles calculations to explore how gold atom migration affects the structural and electrical properties of thiol-gold nano-contacts, revealing alternating rectifying behaviors during pulling.

Contribution

It demonstrates the atomic migration and structural transitions in gold-thiol junctions and their impact on electrical rectification, aligning with experimental observations.

Findings

Gold atoms migrate between electrodes and thiol groups during pulling.

Junction structures alternate between symmetric and asymmetric configurations.

Electrical behavior switches between rectifying and non-rectifying as the junction is stretched.

Abstract

We investigate, by means of first-principles calculations, structural and transport properties of junctions made of symmetric dithiolated molecules placed between Au electrodes. As the electrodes are pulled apart, we find that it becomes energetically favorable that Au atoms migrate to positions between the electrode surface and thiol terminations, with junction structures alternating between symmetric and asymmetric. As a result, the calculated $\emph{IV}$ curves alternate between rectifying and non-rectifying behaviors as the electrodes are pulled apart, which is consistent with recent experimental results.