Photoconduction and low-temperature Ohmic conduction of Peierls conductor o-TaS$_3$ under uniaxial strain

Abstract

The effect of uniaxial strain on the photoconduction $\delta G$ and low-temperature Ohmic conduction $G$ of Peierls conductor o-TaS$_3$ have been studied. Four-contact structure on the base of high-quality o-TaS$_3$ crystal, containing a segment with a strain (1 \%) and one without it, separated by a buffer part, has been prepared for the study. Notable changes both $G(T)$ and $\delta G(T)$ have been observed below $T < 60$~K under uniaxial strain, namely: a plateau of $G(T)$ in the region of activation-law-change becomes wider under the strain, and an additional low-temperature maximum of $\delta G(T)$ appears, its value being even bigger than one of the main maximum of $\delta G(T)$, which is mainly due to single particle excitations. As a result the values of $G(T)$ and $\delta G(T)$ become one order bigger than the ones without strain. The relative changes of $G(T)$ and $\delta G(T)$ under the strain exhibit a sharp step-like growth upon cooling at slightly different temperatures ($\approx 10$~K). The observed features are consistent with a simple model implying strain-induced increase of concentration of solitons which contribute into both conduction and photoconduction.