The ac response of the pinned-charge-density-wave conductor orthorhombic ${\mathrm{TaS}}_3$ at low frequencies is found to be strongly ac-amplitude dependent for amplitudes well below the dc threshold field. In the low-amplitude regime, the behavior is strongly temperature dependent suggesting the existence of thermally activated relaxation processes. The ac-amplitude dependence reflects the presence of a distribution of local pinning fields.

• Received 31 July 1985

DOI:https://doi.org/10.1103/PhysRevB.32.6939