Charge-density-wave pinning and metastable-state dynamics inNbSe3

We have explored transient charge dynamics associated with metastable pinning configurations in both charge-density-wave (CDW) states of ${\mathrm{NbSe}}_3$. The amount of charge associated with the pinned metastable states is less than ${10}^{\mathrm{-}5}$ of the total condensed CDW carrier density. Depinning the CDW results in a transient dynamics with corresponding charge mobilities of the order of ${10}^6$ ${\mathrm{cm}}^2$/V sec, the highest mobility observed for any metallic conductor. At high temperatures in the CDW state, the transient response appears to be correlated with the CDW impurity-pinning strength. At low temperatures (T<40 K), this correlation breaks down, suggesting a sudden and dramatic change in the CDW-impurity interaction strength or, alternatively, a change in the effective CDW carrier density.