Magnetoresistance and thermoelectric power studies of metal-nonmetal transition in iodine-doped polyacetylene

Abstract Highly conducting polyacetylene iodine-doped to saturation level changed from metallic to nonmetallic states by aging, judging from the temperature dependence of the resistivity. During this change, the thermoelectric power did not vary drastically, suggesting that the transition cannot be ascribed to the change in carrier concentration. By contrast the magnetoresistance changed remarkably on crossing the transition. The transition is ascribed to the effect of disorder.