Static magnetic susceptibilities of poly (phenylethynylcopper) doped with iodine

Static magnetic susceptibilities of poly(phenylethynylcopper), doped with iodine, are reported and analysed in view of a simple “dilute” system of paramagnetic centres in a diamagnetic matrix, the unpaired electron concentration being generated by a thermal activation process. The resulting diamagnetism, −3.3 × 10⁻⁹ m³ kg⁻¹, is low suggesting the presence of a temperature independent paramagnetism of ≧ 0.6 × 10⁻⁹ m³ kg⁻¹. The maximum concentration of unpaired electrons accounted for by the data, taken above 160 K, is 3.1 × 10⁻² per mole. The 4.2 K concentration is 8 × 10⁻³ unpaired electrons per mole. The field dependence of the low temperature susceptibility indicates the occurrence of ferromagnetic coupling between unpaired electrons, showing that the “dilute” model does not hold in the low temperature region.