Semiconducting chains of gold and silver

TL;DR

This paper proposes a new stable geometry for ultrathin gold and silver wires, revealing their insulating properties and analyzing the electronic structure effects responsible for this behavior.

Contribution

It introduces a stable, non-planar geometry for Au and Ag wires and demonstrates their insulating nature through ab initio calculations.

Findings

New stable geometry is more stable by 0.1 eV per atom.

Wires are insulating with band gaps up to 1.9 eV.

Insulating behavior is not due to Peierls instability.

Abstract

The authors introduce a geometry for ultrathin Au and Ag wires that ab initio calculations indicate to be more stable than previously considered planar geometries for these systems, by about 0.1 eV per atom. This structure is insulating for both metals and for related Ag_(0.5)-Au_(0.5) alloys, with gaps of 1.3 eV for Au, 0.8 eV for Ag, and varying between 0.1 eV and 1.9 eV for the alloys. The insulating nature of the geometry is not a result of Peierls instabilities, and is analyzed in terms of an interplay between geometric and electronic structure effects.