THERMAL VARIATION OF THE SPIN SUSCEPTIBILITY OF CHAINS OF CONDUCTING POLYMERS

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