We report measurements of the static Young’s modulus of orthorhombic TaS${}_3$ in the drifting charge-density-wave state. In contrast to vibrating-reed and ultrasonic measurements of the Young’s modulus, the static modulus softening was observed to be less than 0.001% for electric fields up to eight times the threshold field for non-Ohmic conduction. A relaxation model using a field-dependent distribution of relaxation times was used to calculate the frequency dependence of the modulus and internal friction anomalies. A comparison with experimental data suggests the possibility that if the softening is relaxational, then a high- and a low-frequency relaxation regime may exist in this material.

• Received 8 July 1992

DOI:https://doi.org/10.1103/PhysRevB.46.12117