First-principles Simulations of the stretching and final breaking of Al nanowires: Mechanical properties and electrical conductance

TL;DR

This paper uses first-principles simulations to study how aluminum nanowires stretch and break, revealing the relationship between structural changes and electrical conductance during failure.

Contribution

It provides a detailed atomic-level understanding of the mechanical and electrical behavior of Al nanowires under stress, aligning with experimental observations.

Findings

Conductance increases to near quantum levels before breaking.

Force changes correlate with structural and conductance modifications.

A dimer contact geometry dominates at the final stages.

Abstract

The evolution of the structure and conductance of an Al nanowire subject to a tensile stress has been studied by first-principles total-energy simulations. Our calculations show the correlation between discontinuous changes in the force (associated to changes in the bonding structure of the nanowire) and abrupt modifications of the conductance as the nanowire develops a thinner neck, in agreement with the experiments. We reproduce the characteristic increase of the conductance in the last plateau, reaching a value close to the conductance quantum $G_0 = 2 e^2 / h$ before the breaking of the nanowire. A dimer defines the contact geometry at these last stages, with three channels (one dominant) contributing to the conductance.