Photoconduction and photocontrolled collective effects in the Peierls conductor TaS${}_3$

Light illumination of thin crystals of CDW conductor TaS${}_3$ is found to result in dramatic changes of both linear ($G$) and nonlinear conduction. The increase of $G$ is accompanied by suppression of the collective conduction, growth of the threshold field $E_T$, and appearance of the switching and hysteretic behavior in the nonlinear conduction. The effects in the nonlinear conduction are associated with increase of CDW elasticity due to illumination that leads in particular to appearance of a relation $E_T\propto G^{1\mathrm{/}3}$ expected for the one-dimensional pinning.