Charge-density-wave conduction: Dynamics and finite-size effects

Abstract

The charge-density-wave dynamics in samples with size on the order of a Lee-Rice domain are calculated. At high frequency and current the conductivity approaches that of infinite samples. An explanation for the apparent discrepancy between measurements at large currents and the asymptotic behavior derived by Sneddon, Cross, and Fisher is presented. Finite-size effects change the response at low frequency and current. A kink is introduced in dV/dI near the threshold for dc conduction. Our results agree quantitatively with experiments on some ${\mathrm{NbSe}}_3$ samples. The ac response is found to be substantially broader than the overdamped harmonic-oscillator form which has been used to describe experimental results. The response is characteristic of a distribution of relaxation times similar to that observed in recent experiments. This distribution is related to the elastic modes of the deformable charge-density-wave condensate. A relation between the frequency and current dependence of the damping by these modes is derived. Our results are compared with those for infinite samples.