Palladium wires of single atom width as mechanically controlled switching devices

Palladium (Pd) wires of single atom width, prepared by contact and successive retraction of two nanometer-sized Pd tips, were observed by in situ transmission electron microscopy with simultaneous measurements of force and conductance. The Pd wires, composed of three atoms, grew along the retraction direction of the tip. The interatomic distance was 0.30 +/- 0.05 nm. The maximum force acting on the Pd wires was 0.42 +/- 0.05 nN. The current through the Pd wires was 0.2 mu A at 100 mV. In accordance with the correlation between current and force, we proposed a mechanically controlled current switching device using atomic wires.