Harmonic generation and scaling behavior in sliding-charge-density-wave conductors

The generation of harmonics of a small ac modulation field is used, in conjunction with the standard current-voltage measurement, to study the depinning behavior in well-characterized and high-purity samples of the charge-density-wave conductor NbSe₃. The results show that the current carried by the charge density wave obeys a scaling law: I_CDW=[(V-VT)/VT]^ζ with {ζ}=1.23±{}0.07. Implications of this result on the various theoretical models of the dynamics of the sliding state are discussed.