Mechanically-controllable single molecule switch based on configuration specific electrical conductivity of metal-molecule-metal junctions

We report the systematic characterization of configuration-specific electrical conductivity in metal-molecule-metal structures for a demonstration of mechanically controllable contact effect single-molecule switches. Break junction measurements reveal two distinct conductance states of G(H) similar to 1.3 mG(0) and G(L) similar to 0.4 mG(0) in an Au hexanedithiol Au system. We provide evidence that transitions from G(H) to G(L) involve atom scale deformations between two distinct metal-molecule contact configurations by conducting single molecule inelastic electron tunneling spectroscopy. We also examine mechanically controlled binary switching via bistable conductance states, thereby attaining an alkanedithiol single-molecule switch.