Understanding the structure of the first atomic contact in Gold

TL;DR

This study combines experimental observations, molecular dynamics simulations, and quantum transport calculations to analyze the atomic structure and conductance behavior of gold contacts during formation and rupture, elucidating JC and JOC phenomena.

Contribution

It provides a detailed atomic-level understanding of gold contact formation and rupture, integrating experimental data with simulations and first-principles calculations.

Findings

Reproducible conductance behavior at limited indentation depths

Identification of crystallographic tip structures formed through mechanical annealing

Correlation between atomic configurations and conductance in JC and JOC events

Abstract

We have studied experimentally the phenomena of jump-to-contact (JC) and jump-out-of-contact (JOC) in gold electrodes. JC can be observed at the first contact when the two metals approach each other while JOC occurs in the last contact before breaking. When the indentation depth between the electrodes is limited to a certain value of conductance, a highly reproducible behaviour in the evolution of the conductance can be obtained for hundreds of cycles of formation and rupture. Molecular dynamics simulations of this process show how the two metallic electrodes are shaped into tips of a well-defined crystallographic structure formed through a mechanical annealing mechanism. We report a detailed analysis of the atomic configurations obtained before contact and rupture of these stable structures and obtained their conductance using first-principlesquantum transport calculations. These results help us understand the values of conductance obtained experimentally in the JC and JOC phenomena and improve our understanding of atomic-sized contacts and the evolution of their structural characteristics.