Conductivity and magnetoconductivity below 1 K in films of poly(3,4-ethylenedioxythiophene) doped with CF3SO3

The temperature dependence of the electrical conductivity σ(T) and the magnetoconductivity σ(B,T) of poly(3,4-ethylenedioxythiophene) (PEDOT) films heavily doped with CF3SO3 has been measured down to T = 150 mK in magnetic fields up to B = 9 T. It is shown that, below 1 K, σ(T) α ln T and σ(B,T) depends significantly on the orientation of B parallel or perpendicular to the film surface. These facts are interpreted as a manifestation of two-dimensional character of electron transport in highly doped PEDOT films because of the possible formation of strongly graphitized layers with plane structure of polymer chains or fibrils.