Electronic and atomic shell structure in aluminum nanowires

TL;DR

This study investigates aluminum nanowires, revealing two distinct stable structure regimes governed by electronic shell effects at low conductance and atomic packing at higher conductance, with a unique superdeformed wire series.

Contribution

It provides the first detailed experimental and theoretical analysis of shell effects in aluminum nanowires, highlighting a unique stable wire series not seen in other metals.

Findings

Identification of two stable structure regimes in aluminum nanowires.

Observation of a unique series of superdeformed nanowires.

Smooth crossover between electronic and atomic shell effects.

Abstract

We report experiments on aluminum nanowires in ultra-high vacuum at room temperature that reveal a periodic spectrum of exceptionally stable structures. Two "magic" series of stable structures are observed: At low conductance, the formation of stable nanowires is governed by electronic shell effects whereas for larger contacts atomic packing dominates. The crossover between the two regimes is found to be smooth. A detailed comparison of the experimental results to a theoretical stability analysis indicates that while the main features of the observed electron-shell structure are similar to those of alkali and noble metals, a sequence of extremely stable wires plays a unique role in Aluminum. This series appears isolated in conductance histograms and can be attributed to "superdeformed" non-axisymmetric nanowires.