Transport properties of single atoms

TL;DR

This paper systematically investigates ballistic electron conductance through single sp and 3d transition metal atoms connected to copper and palladium electrodes, revealing how atomic and electronic properties influence conductance channels.

Contribution

It provides a detailed microscopic classification of conductance channels based on atomic orbitals and symmetry, using ab initio calculations and the Kubo approach.

Findings

Conductance mainly depends on the electronic properties of the bridging atom.

Impurity resonances at the Fermi level can open or block conductance channels.

The study offers a microscopic understanding of conductance variations in atomic-scale contacts.

Abstract

We present a systematic study of the ballistic electron conductance through sp and 3d transition metal atoms attached to copper and palladium crystalline electrodes. We employ the 'ab initio' screened Korringa-Kohn-Rostoker Green's function method to calculate the electronic structure of nanocontacts while the ballistic transmission and conductance eigenchannels were obtained by means of the Kubo approach as formulated by Baranger and Stone. We demonstrate that the conductance of the systems is mainly determined by the electronic properties of the atom bridging the macroscopic leads. We classify the conducting eigenchannels according to the atomic orbitals of the contact atom and the irreducible representations of the symmetry point group of the system that leads to the microscopic understanding of the conductance. We show that if impurity resonances in the density of states of the contact atom appear at the Fermi energy, additional channels of appropriate symmetry could open. On the other hand the transmission of the existing channels could be blocked by impurity scattering.