LOW-TEMPERATURE MAGNETIC-PROPERTIES FOR POLY(3-ALKYLTHIOPHENES) AND POLY(4,4'-DIALKYL-2,2'-BITHIOPHENES)

Thin films of soluble conjugated polymers doped with FeCl4-, were inve stigated, namely: poly(3-alkylthiophenes) and their 'head to head' ('' tail to tail') coupled analogues: poly(4,4'-dialkyl-2,2'-bithiophenes) where alkyl = hexyl, octyl and decyl. Two temperature ranges of diffe rent magnetic behaviour can be distinguished, i.e: i) high temperature one, where the system obeys the Curie law and the samples behave as a classical paramagnetic material, ii) low temperature one, where a 'sh ort range' magnetic order of dopants mediated by bipolarons affects ma gnetic response of the polymer samples.