Nonlinear Conductivity and Noise in the Quasi One-Dimensional Blue BronzeK0.30MoO3

Nonlinear electrical conductivity associated with a large noise voltage has been observed in the semiconducting charge-density-wave state of the blue bronze ${\mathrm{K}}_{0.30}$Mo${\mathrm{O}}_3$. A well defined and strongly temperature-dependent threshold field for the onset of the nonlinear conductivity is found. Both broadband noise and quasiperiodic noise are detected above the treshold field. These results, including the observation of long relaxation times, are discussed in relation with the current models for charge-density-wave transport.