Discrete thinning dynamics in a continuum model of metallic nanowires

TL;DR

This paper demonstrates that a continuum nanoscale free-electron model can replicate the discrete thinning process observed in metallic nanowires, highlighting electron-shell effects and kink dynamics.

Contribution

It introduces a continuum model that captures discrete thinning and kink dynamics in nanowires, aligning with experimental observations.

Findings

Electron-shell effects stabilize certain wire radii.

Kink formation and movement mimic experimental thinning.

Rich kink interactions influence nanowire stability.

Abstract

Transmission electron microscopy experiments have recently observed gold metal nanocylinders to thin down in a discrete manner: A kink--a step of order of one atomic layer--nucleates at one end and then moves along the wire, leaving a thinner cylinder behind it. In this paper, I show that a similar thinning process takes place within the nanoscale free-electron model, a structural and dynamical model of nanowires that treats the electron-confinement effects exactly while replacing the atomic structure by a continuum. Electron-shell effects, previously shown to be responsible for the stability of wires with magic radii, favor the formation of kinks connecting magic cylinders. A rich kink dynamics including interkink interactions ensues and is similar to that observed experimentally.