Magnetic-susceptibility and magnetization measurements of polyacenic semiconductive materials.

Abstract

Magnetic-susceptibility and magnetization measurements of several kinds of polyacenic semiconductive (PAS) materials prepared from the heat treatment (470--750 \ifmmode^\circ\else\textdegree\fi{}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 1/2S1 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.