Thermal hysteresis in the dielectric response of the charge density wave system o-TaS3

The low frequency dielectric response of the charge density wave (CDW) system o-TaS3 exhibits a rate-independent hysteresis on temperature cycling in a very wide temperature range below the CDW transition temperature. The ac conductivity, related to the CDW dynamics, is higher on heating than on cooling, while the dc conductivity of residual free carriers is lower, indicating a nontrivial relation between the two of them. Both the amplitude and the relaxation time of the low frequency relaxation process observed in the temperature region of the hysteresis are higher on heating, with similar temperature dependence to the hysteresis in the dc resistivity. The results indicate that the hystereses in ac and dc conductivities are mainly coupled through the free carrier screening of the CDW phase and not through the conversion of free carriers into phase defects.