Microscopic origin of the conducting channels in metallic atomic-size contacts

TL;DR

This paper introduces a theoretical method to identify the number and orbital nature of conduction channels in metallic atomic contacts, aligning well with experimental data and demonstrating robustness against disorder.

Contribution

A novel theoretical approach to determine the number and orbital character of conduction channels in metallic atomic contacts, validated by experimental agreement.

Findings

Number of channels: 3 for Al, 5 for Nb

Channels are derived from atomic orbitals near the Fermi level

Results are robust against disorder

Abstract

We present a theoretical approach which allows to determine the number and orbital character of the conducting channels in metallic atomic contacts. We show how the conducting channels arise from the atomic orbitals having a significant contribution to the bands around the Fermi level. Our theory predicts that the number of conducting channels with non negligible transmission is 3 for Al and 5 for Nb one-atom contacts, in agreement with recent experiments. These results are shown to be robust with respect to disorder. The experimental values of the channels transmissions lie within the calculated distributions.