Novel ferromagnetic behavior of conducting polymers doped with fullerene and TDAE

Magnetic behavior of composites of C60 and some soluble conducting polymers such as poly(3-alkylthiophene) and poly(2,5-dioctyloxyphenylene vinylene) has been studied by ESR measurements. Spin-susceptibility depends on temperature markedly and the positive Weiss constants are observed after doping of donor molecules, TDAE, indicating ferromagnetic spin exchange interaction. Dependence of the magnetic behavior on the thermal treatment and molecular structure of host conducting polymer is discussed.