Current-voltage characteristics of conducting polymers and carbon nanotubes

The electronic transport properties of a number of materials with nanoscale or microscale structure show some remarkable similarities despite the differing conduction mechanisms expected in different materials, for example similar nonlinearities in their current-voltage characteristics. We propose a generic expression for the nonlinear current-voltage characteristics based on our numerical calculations for metallic conduction interrupted by small barriers. We discuss the general features of the experimental data and show that our expression gives a very good description of the observed nonlinearities in carbon nanotube networks, vanadium pentoxide nanofibres and polyacetylene nanofibres, as well as half-metallic granular Sr2FeMoO6 that is of interest for spintronics.