Observation of fluctuation modulation of tunnel junctions by applied ac stress in carbon polyvinylchloride composites

Modulation of small tunneling barriers by thermally activated voltage fluctuations is observed in the composite material carbon polyvinylchloride consisting of large conducting carbon chains and aggregates separated by narrow insulating gaps. The effect is experimentally determined by applying an ac stress to the sample and measuring the change in resistivity per unit strain as a function of temperature. After determining the tunneling parameters $T_0$ and $T_1$ from the temperature dependence of the resistivity, the temperature dependence of the change in resistivity per unit strain is calculated based on the fluctuation-induced tunneling theory in which the tunneling barrier is lowered and narrowed by thermally activated voltage fluctuations. Good agreement is obtained between the experimental results and the fluctuation-induced tunneling theory.