CHARGE-DENSITY-WAVE PINNING AND METASTABLE-STATE DYNAMICS IN NBSE3

We have explored transient charge dynamics associated with metastable pinning configurations in both charge-density-wave (CDW) states of NbSe3. The amount of charge associated with the pinned metastble states is less than 10(-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) cm2/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.