Wide-temperature-range dielectric response of the charge-density-wave system ${\mathrm{TaS}}_3$

We present a detailed investigation of the low-frequency dielectric response of the charge-density-wave system (CDW) $o-{\mathrm{TaS}}_3$ in wide temperature (5–300 K) and frequency (10 mHz to 100 MHz) ranges. Although our measurements agree relatively well with data performed in some restricted frequency and temperature ranges and previously published by several groups, we show that they do not correspond to a single low-frequency process. Instead, three distinctive processes are found to contribute to the dielectric function below the CDW transition temperature. The temperature evolution of the characteristic relaxation time of the three processes bears a close resemblance to the phenomenology of the dielectric response of glasses. The freezing of some of these processes at finite temperatures leads to changes in the CDW properties, as is thoroughly documented in the literature. Based on these results, we propose a consistent model of the temperature evolution of the CDW ground state.