Mechanical annealing of metallic electrodes at the atomic scale

TL;DR

This paper demonstrates how repeated mechanical indentation of gold electrodes leads to the formation of reproducible, atomically defined metallic tips, combining experiments and simulations to understand the process at the atomic scale.

Contribution

It introduces a method of mechanical annealing to produce stable, atomically defined metallic tips through repeated indentation, supported by experimental and computational analysis.

Findings

Repeated indentation results in reproducible metallic tips.

Conductance behavior stabilizes after multiple cycles.

Simulations confirm atomic-scale tip shaping.

Abstract

The process of creating an atomically defined and robust metallic tip is described and quantified using measurements of contact conductance between gold electrodes and numerical simulations. Our experiments show how the same conductance behavior can be obtained for hundreds of cycles of formation and rupture of the nanocontact by limiting the indentation depth between the two electrodes up to a conductance value of approximately $5G_{0}$ in the case of gold. This phenomenon is rationalized using molecular dynamics simulations together with density functional theory transport calculations which show how, after repeated indentations (mechanical annealing), the two metallic electrodes are shaped into tips of reproducible structure. These results provide a crucial insight into fundamental aspects relevant to nano-tribology or scanning probe microscopies.