High-bias stability of monatomic chains

TL;DR

This paper investigates the high-bias stability and breaking mechanisms of monatomic metal chains of Au, Pt, and Ir, highlighting the roles of current-induced heating and electromigration, with models explaining the observed behaviors.

Contribution

It provides a detailed analysis of the breaking mechanisms of monatomic chains under high bias, applying and validating existing models for Au and Pt metals.

Findings

High-bias breaking voltage decreases inversely with chain length.

Good agreement with models for Au chains, parameters for Pt less independently determined.

Atomic chains can sustain large current densities before failure.

Abstract

For the metals Au, Pt and Ir it is possible to form freely suspended monatomic chains between bulk electrodes. The atomic chains sustain very large current densities, but finally fail at high bias. We investigate the breaking mechanism, that involves current-induced heating of the atomic wires and electromigration forces. We find good agreement of the observations for Au based on models due to Todorov and coworkers. The high-bias breaking of atomic chains for Pt can also be described by the models, although here the parameters have not been obtained independently. In the limit of long chains the breaking voltage decreases inversely proportional to the length.