Screened dynamics of sliding charge density waves.

I study the response of charge density waves, randomly pinned by disorder and in the presence of uncondensed carriers. Backflow screening currents of normal carriers lead to enhanced dissipation for CDW motion at low frequency and temperature. A crossover in the damping mechanism at a frequency sigma/epsilon sub 0 leads to the emergence of two characteristic loss peaks in the ac response, and bistability of the CDW-I-V characteristic.