Effect of magnetic dopant on the metallic conductance of polyacetylene at low temperature

The low-temperature metallic conductance in FeCl₄^-- and ClO₄^--doped polyacetylene has been studied with the aim to probe the conduction electron-dopant interaction. A different behavior ascribable to the magnetic moment at the dopant site was found below ~1 K under a magnetic field of less than ~1 T. The result is discussed with respect to the effect of scattering by localized spins at the FeCl₄^- site. The logarithmic temperature dependence and the negative magnetoresistance are examined in relation to spin scattering at the magnetic dopant and at the carbonyl basis, and to pseudospin scattering due to dynamic chain distortion. The effect of inhomogeneity is discussed also.