Mechanical properties of Pt monatomic chains

TL;DR

This study investigates the mechanical properties of platinum monatomic chains using a novel measurement technique, revealing how chain configuration and initial stiffness influence elongation and breaking behavior.

Contribution

It introduces a new MCBJ technique with a tuning fork sensor to simultaneously measure stiffness and conductance during chain elongation.

Findings

Stiffness and conductance increase then decrease before breaking

Peaks in length-histogram correlate with chain atom count

Softer chains can be stretched longer

Abstract

The mechanical properties of platinum monatomic chains were investigated by simultaneous measurement of an effective stiffness and the conductance using our newly developed mechanically controllable break junction (MCBJ) technique with a tuning fork as a force sensor. When stretching a monatomic contact (two-atom chain), the stiffness and conductance increases at the early stage of stretching and then decreases just before breaking, which is attributed to a transition of the chain configuration and bond weakening. A statistical analysis was made to investigate the mechanical properties of monatomic chains. The average stiffness shows minima at the peak positions of the length-histogram. From this result we conclude that the peaks in the length-histogram are a measure of the number of atoms in the chains, and that the chains break from a strained state. Additionally, we find that the smaller the initial stiffness of the chain is, the longer the chain becomes. This shows that softer chains can be stretched longer.