Influence of relativistic effects on the contact formation of transition metals

TL;DR

This study investigates how relativistic effects influence contact formation in transition metals, showing that gold exhibits longer-range interactions due to relativistic energy contributions, affecting contact distances.

Contribution

It demonstrates the impact of relativistic effects on atomic contact formation distances in gold compared to silver and copper, supported by ab initio calculations.

Findings

Gold contacts form at longer distances than Ag or Cu.

Relativistic effects significantly influence gold's electronic structure.

Contact conductance is mainly determined by geometry and coordination.

Abstract

Our analysis of the contact formation processes undergone by Au, Ag and Cu nanojunctions, reveals that the distance at which the two closest atoms on a pair of opposing electrodes jump into contact is, on average, two times longer for Au than either Ag or Cu. This suggests the existence of a longer range interaction between those two atoms in the case of Au, a result of the significant relativistic energy contributions to the electronic structure of this metal, as confirmed by ab initio calculations. Once in the contact regime, the differences between Au, Ag and Cu are subtle, and the conductance of single-atom contacts for metals of similar chemical valence is mostly determined by geometry and coordination.