Formation of a Metallic Contact: Jump to Contact Revisited

TL;DR

This study investigates the transition from tunneling to metallic contact, revealing that electrode configuration and material influence whether a jump occurs, and identifies conductance values associated with specific atomic contact structures.

Contribution

It combines experiments, molecular dynamics, and first-principles calculations to clarify the atomic origins of conductance jumps in metallic contact formation.

Findings

Presence or absence of jumps depends on electrode configuration and material.

Identified conductance values correspond to atomic contacts of monomers, dimers, or double bonds.

Jumps are associated with specific atomic contact structures.

Abstract

The transition from tunneling to metallic contact between two surfaces does not always involve a jump, but can be smooth. We have observed that the configuration and material composition of the electrodes before contact largely determines the presence or absence of a jump. Moreover, when jumps are found preferential values of conductance have been identified. Through combination of experiments, molecular dynamics, and first-principles transport calculations these conductance values are identified with atomic contacts of either monomers, dimers or double-bond contacts.