Frequency dependence of elastic anomalies in charge-density-wave conductors

We have measured the frequency dependence of the Youngs-modulus (Y) and internal-friction anomalies in the charge-density-wave conductors NbSe3 and TaS3. Measurements were made on overtones of flexural resonances using a helical resonator detector between 1 and 100 kHz. Temperature-dependent anomalies were independent of frequency, whereas electric-field-dependent anomalies decreased rapidly with frequency; e.g., Y/Y -p, where p(3/4. These results are inconsistent with all models proposed of the elastic properties of the charge-density-wave state.