Conductance of single-atom platinum contacts: Voltage-dependence of the conductance histogram

TL;DR

This study investigates how the conductance of single-atom platinum contacts varies with voltage, revealing a strong voltage dependence influenced by hydrogen inclusion and electron current effects.

Contribution

It demonstrates the voltage-dependent conductance behavior of platinum atomic contacts and suggests hydrogen's role in observed conductance variations.

Findings

Conductance values range from 1 to 2.5 times 2e^2/h depending on bias.

Hydrogen inclusion affects the conductance histogram peaks.

High bias destabilizes platinum monatomic chains.

Abstract

The conductance of a single-atom contact is sensitive to the coupling of this contact atom to the atoms in the leads. Notably for the transition metals this gives rise to a considerable spread in the observed conductance values. The mean conductance value and spread can be obtained from the first peak in conductance histograms recorded from a large set of contact-breaking cycles. In contrast to the monovalent metals, this mean value for Pt depends strongly on the applied voltage bias and other experimental conditions, ranging from about 1 to 2.5 times 2e^2/h. We propose that the different results in part can be explained by the inclusion of hydrogen in the contacts. The bias dependence of the conductance is on the other hand due to the electron current that destabilizes monatomic Pt chains at high bias.