MAGNETIC STUDIES OF FECL4(-)-DOPED POLY(3-ALKYLTHIOPHENES) AND POLY(4,4'-DIALKYL-2,2'-BITHIOPHENES)

Two types of soluble conducting polymers doped with FeCl4- were investigated, namely, poly(3-alkylthiophenes) and their ''head-to-head,'' ''tail-to-tail'' coupled analogues: poly(4,4'-dialkyl-2,2'-bithiophenes). The samples were subjected to static magnetic measurements of the magnetic susceptibility (the Faraday balance) and electron-spin-resonance spectroscopy in a wide temperature range (4.2-273 K). A classical paramagnetic dependence of the static magnetic susceptibility can be found at high temperatures. On the other hand, a different magnetic effect appears at low temperatures. This may suggest that below a certain temperature (denoted as T(a)), short-range magnetic order affects the magnetic response of the polymer samples.