Quantum fluctuations in the cohesive force of metallic nanowires

TL;DR

This paper investigates quantum fluctuations in the cohesive force of metallic nanowires, revealing their dependence on electronic states near the Fermi energy and linking fluctuations to classical periodic orbits.

Contribution

It extends the free electron model to quantify quantum force fluctuations in nanowires and connects these fluctuations to classical periodic orbits using the Balian-Bloch trace formula.

Findings

Force fluctuations are dominated by states near the Fermi energy.

Fluctuations are of order epsilon_F/lambda_F.

Classical periodic orbits effectively describe the fluctuations.

Abstract

Based on the recent free electron model for cohesion in narrow metallic constrictions by Stafford et al., we calculate the quantum fluctuations in the cohesive force versus elongation. The fluctuations are dominated by states near the Fermi energy, thus explaining their apparently universal magnitude of order epsilon_F/lambda_F. We present numerical results for the force fluctuations in a simple geometry and show that they are well described by the contributions of a few classical periodic orbits in the Balian-Bloch trace formula for the density of states of transverse motion.