Fluctuation-Induced Tunneling Conduction in Carbon-Polyvinylchloride Composites

We present evidence that in carbon-polyvinylchloride composites, consisting of aggregates of carbon spheres (100-400 Å) dispersed in the insulating matrix, the electrical conductivity can be ascribed to a novel mechanism of tunneling with potential-barrier modulation by thermal fluctuations. Theoretical consideration of the tunneling-probability modification by thermal fluctuating electric field across tunnel junctions yields expressions for the temperature and the field dependences of the conductivity in excellent accord with experimental results.