Mechanical Strain, Conductance Fluctuations, and Dynamics of Single Tunneling Defects

David Hoadley and Norman O. Birge

Department of Physics and Astronomy, Michigan State University

The SEM micrograph shows a bismuth wire about 60nm in width. The vertical lines are leads attaching the sample to contact pads and ultimately measurement devices. The left and right arms of the sample form the bottom half of a Wheatstone bridge, which is designed to measure differences in resistance between the two arms. At temperatures near absolute zero ( around 1K ), single mobile defects can change such a sample's resistance by a few Ohms, producing a random telegraph signal as the defect moves from one meta-stable state to another. We are using this device to study the effect of planar strain on the dynamics of individual mobile defects.