Reversible electromechanical characteristics of carbon nanotubes underlocal-probe manipulation

The effects of mechanical deformation on the electrical properties of carbonnanotubes are of interest given the practical potential of nanotubes in electromechanicaldevices, and they have been studied using both theoretical 1 , 2 , 3 , 4 and experimental 5 , 6 approaches. One recent experiment 6 used the tip of an atomic force microscope (AFM) to manipulate multi-wallednanotubes, revealing that changes in the sample resistance were small unlessthe nanotubes fractured or the metal–tube contacts were perturbed. Butit remains unclear how mechanical deformation affects the intrinsic electricalproperties of nanotubes. Here we report an experimental and theoretical elucidationof the electromechanical characteristics of individual single-walled carbonnanotubes (SWNTs) under local-probe manipulation. We use AFM tips to deflectsuspended SWNTs reversibly, without changing the contact resistance; insitu electrical measurements reveal that the conductance of an SWNT samplecan be reduced by two orders of magnitude when deformed by an AFM tip. Ourtight-binding simulations indicate that this effect is owing to the formationof local sp 3 bonds caused by the mechanical pushingaction of the tip.