Low-temperature saturation of dephasing in heavily doped polyacetylene

Based on studies of low-temperature electronic transport in heavily doped polyacetylene, we provide evidence that the low-temperature saturation of electron dephasing reported earlier for metallic and semiconducting materials [P. Mohanty, E.M.Q. Jariwala, and R.A. Webb, Phys. Rev. Lett. 78, 3366 (1997)] is also exhibited in conducting polymers. We suggest a simple model to explain such behavior that involves electron dephasing by two-level systems of a special type originating from initially symmetric defect configurations where the symmetry is partially lifted by disorder.