Dependence of the dielectric response of the charge-density wave inK0.3MoO3on ac signal amplitude

We have measured the dielectric response of the charge-density wave (CDW) in ${\mathrm{K}}_{0.3}$Mo${\mathrm{O}}_3$ at 77 K for ac signal amplitudes between 2% and 18% of the threshold field ($E_T$) for CDW transport. For ac signal levels less than approximately 10% of $E_T$ the intrinsic relaxation of the CDW is probed. For larger ac levels the response is nonlinear as the CDW is driven into metastable states with longer relaxation times. The mean relaxation time increases for large ac signal levels as the proportion of long-time processes increases.