Frequency and Electric Field Dependence of the Conductivity of Metallic Polyacetylene

Abstract

The temperature ($T$), frequency ($f$), and electric field ($E$) dependent conductivity ($\ensuremath{\sigma}$) of iodine-doped polyacetylene is reported for the concentration regime which encompasses the metal-insulator transition. No $f$ dependence was observed for $f<500$ MHz. The resistance varied logarithmically with $E$, while $\ensuremath{\sigma}\ensuremath{\sim}\mathrm{ln}T$ and $\ensuremath{\sigma}\ensuremath{\sim}\mathrm{exp}[\ensuremath{-}{(\frac{{T}_{A}}{T})}^{0.25}]$ were observed. This $\ensuremath{\sigma}(T,E,f)$ is inconsistent with simple models of metallic regions separated by large barriers and suggests that the known strong disorder plays a dominant role.