Electron Standing Wave Formation in Atomic Wires

TL;DR

This paper investigates electron transport in atomic wires using theoretical models, revealing how standing waves and contact chemistry influence conductance, with results aligning with experimental and previous theoretical findings.

Contribution

It introduces a detailed analysis of electron standing wave formation in atomic wires and examines the impact of contact chemistry on conductance oscillations.

Findings

Gold wires have conductance around 1 G_0, consistent with experiments.

Carbon wires exhibit conductance oscillations with chain length, favoring odd-numbered chains.

Contact chemistry significantly affects electron standing wave patterns.

Abstract

Using the Landauer formulation of transport theory and tight binding models of the electronic structure, we study electron transport through atomic wires that form 1D constrictions between pairs of metallic nano-contacts. Our results are interpreted in terms of electron standing waves formed in the atomic wires due to interference of electron waves reflected at the ends of the atomic constrictions. We explore the influence of the chemistry of the atomic wire-metal contact interfaces on these standing waves and the associated transport resonances by considering two types of atomic wires: gold wires attached to gold contacts and carbon wires attached to gold contacts. We find that the conductance of the gold wires is roughly $1 G_0 = 2 e^2/h$ for the wire lengths studied, in agreement with experiments. By contrast, for the carbon wires the conductance is found to oscillate strongly as the number of atoms in the wire varies, the odd numbered chains being more conductive than the even numbered ones, in agreement with previous theoretical work that was based on a different model of the carbon wire and metal contacts.