Mechanical properties of Pt monatomic chains

The mechanical properties of Pt monatomic chains were investigated by a simultaneous measurement of effective stiffness and conductance using our recently developed mechanically controllable break junction 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.