Effect of bonding of a CO molecule on the conductance of atomic metal wires

TL;DR

This study investigates how bonding a CO molecule affects the electrical conductance of atomic-scale metal contacts, revealing a fractional conductance feature near 0.5 G0 that varies with bias voltage.

Contribution

It provides experimental evidence of CO bonding effects on conductance in various metals and shows how bias voltage influences the conductance features, especially in gold contacts.

Findings

A conductance feature near 0.5 G0 appears upon CO bonding.

The feature's intensity can be tuned with bias voltage.

CO bonding to Au is weakest and linked to monoatomic wire formation.

Abstract

We have measured the effect of bonding of a CO molecule on the conductance of Au, Cu, Pt, and Ni atomic contacts at 4.2 K. When CO gas is admitted to the metal nano contacts, a conductance feature appears in the conductance histogram near 0.5 of the quantum unit of conductance, for all metals. For Au, the intensity of this fractional conductance feature can be tuned with the bias voltage, and it disappears at high bias voltage (above $\sim$ 200 mV). The bonding of CO to Au appears to be weakest, and associated with monotomic Au wire formation.