Soliton photoconduction in the charge-density-wave conductor orthorhombic TaS$_3$

The effect of uniaxial strain on low-temperature conduction and photoconduction of the Peierls conductor orthorhombic TaS$_3$ is studied. A consistent increase in the conductance and photoconductance at $T$ $60$ K, was found, contradicting the collisional recombination model, which well describes photoconduction in unstrained samples. The increase in conductance is accompanied by an increase in the threshold field for onset of charge-density-wave sliding, $E_{\mathrm{T}}$, and the relationship between $E_{\mathrm{T}}$ and the conductance is similar to that observed in the case of photoconduction. This relationship is caused by a change in the screening conditions of the charge density wave owing to a change in the current carrier concentration. A change in the character of the charge-density-wave pinning from three-dimensional at $T$ $60$ K to one-dimensional at $T$ $45$ K under $e \approx 0.5\%$ elongation is observed. The effects are explained by the fact that under the strain, the contribution of solitons to both low-temperature conduction and photoconduction becomes dominant.