Stability of metal nanowires at ultrahigh current densities

Abstract

We develop a generalized grand canonical potential for the ballistic nonequilibrium electron distribution in a metal nanowire with a finite applied bias voltage. Coulomb interactions are treated in the self-consistent Hartree approximation, in order to ensure gauge invariance. Using this formalism, we investigate the stability and cohesive properties of metallic nanocylinders at ultrahigh current densities. A linear stability analysis shows that metal nanowires with certain magic conductance values can support current densities up to 10 11 A/cm 2 , which would vaporize a macroscopic piece of metal. This finding is consistent with experimental studies of gold nanowires. Interestingly, our analysis also reveals the existence of reentrant stability zones-geometries that are stable only under an applied bias.

Electromigration and the structure of metallic nanocontacts

“…Similar results were found for Al and Au, but the transition was observed to occur at high voltages (0.8 V and 2.4 V) compared to Pt (0.3-0.4 V) (Mizobata et al, 2003). It has been shown by calculations that metallic wires with "magic" conductance values are stable under large current densities (Zhang et al, 2005). The word magic is used here to describe shell effects in analogy with the magic numbers of atoms of few-atom clusters in the gas phase.…”

On the stability and structural dynamics of metal nanowires

“…Indeed, the principal stable zones shown in Fig. 3 were found [26] to persist up to bias voltages eV ≥ 0.1ε F , implying that these wires can support current densities greater than 10 10 A/cm 2 , which would vaporize a macroscopic wire. (See Sec.…”

Stability and symmetry breaking in metal nanowires: The nanoscale free-electron model

“…The electron motion is free along the wire, and confined in the transverse directions. Due to the excellent screening 28,29 in metal wires with G > G 0 , where G 0 = 2e 2 /h is the conductance quantum, electron-electron interactions can in most cases be neglected. The surface properties of various metals can be fit by using appropriate surface boundary conditions.…”

“…On the other hand, the shell correction δΩ can be shown, based on very general arguments, 29,33,34 to be a single-particle effect, which is well described by the NFEM.…”