Charge density wave transport in irradiated orthorhombic TaS₃

Dynamic resistance, noise spectrum and electron diffraction studies on electron irradiated orthorhombic TaS₃ were performed in the temperature range of 75 K-280 K. At low defect concentrations (< 10^-4 displacement per Ta atoms) the threshold field of the nonlinear conductivity (E_T) increases linearly with the irradiation dose in spite of the fact that there is hardly any effect on the Peierls transition temperature, T_p = 221 K. Concomitantly the sharp peaks in the noise spectrum are smeared out and the broad band noise level increases. At higher defect concentrations, Tp decreases and the transverse coherence of CDWs is lost. In this regime the sharp threshold disappears from the nonlinear characteristics.