Anomalous Ultrasonic Attenuation due to Sliding Charge-Density Waves

The influence of sliding charge-density waves on the elastic properties of quasi-one-dimensional conductors is investigated. By use of an extension of the Fukuyama-Lee-Rice model the imaginary part of the self-energy of acoustic phonons is shown to diverge in lowest-order perturbation theory above the threshold field. With the summation of leading divergent contributions, the resulting expressions account well for the observed field dependence of the elastic modulus and the ultrasonic attenuation $\ensuremath{\alpha}$. In particular, a ${\ensuremath{\omega}}^{\frac{3}{2}}$, instead of the usual ${\ensuremath{\omega}}^{2}$, law is predicted for $\ensuremath{\alpha}$ above the threshold field.