THERMAL VARIATION OF THE SPIN SUSCEPTIBILITY OF CHAINS OF CONDUCTING POLYMERS

We investigate theoretically the temperature and doping variation of t he spin susceptibility of a conducting polymer chain. Disorder is trea ted in the framework of statistical models. The qualitative behaviour of such models at low temperature is changed, thus removing the appare nt contradiction with present experiments in poly(aniline). It is show n that both the variation of the Curie coefficient and of the apparent Pauli contribution can be explained without any reference to delocali zed electrons at the Fermi level. Interactions between polarons and bi polarons are shown to modify the spin versus charge relationship, and to be capable of enhancing the spin susceptibility.