Magnetic-susceptibility and magnetization measurements of polyacenic semiconductive materials

Magnetic-susceptibility and magnetization measurements of several kinds of polyacenic semiconductive (PAS) materials prepared from the heat treatment (470–750 °C) of phenol-formaldehyde resin were carried out using the Faraday-balance method. Magnetic parameters were determined from the analysis of the magnetic susceptibility measured in the temperature range 2–260 K. The temperature dependence of the magnetic susceptibility of each sample obeys a weak Curie-Weiss-type law. Analyses of the magnetization curves observed in the magnetic-field range 0–5 T have shown that the total spin quantum number S of the pristine PAS samples is in the range 1/2<S<1 and that of the ${\mathrm{I}}_2$-doped sample is S=1/2. Connection between the magnetic properties obtained here and electrical conductivity will be discussed in detail.