Dynamic scaling during CDW relaxation from the sliding state

Abstract
Using time-resolved high-resolution x-ray scattering techniques, we have measured the evolution of the structure of the Q₁ charge-density wave in NbSe₃ as it relaxes after an applied electric field is turned off. Measurements were made at temperatures between 70 and 120 K and at applied field strengths up to 40x the threshold for sliding. These time-dependent structural data are accurately described by dynamic scaling theory. For threshold field strengths less than the threshold to sliding, the value of the dynamic scaling exponent µ is consistent with the value predicted by assuming that the CDW is an elastic medium. However, for field strengths greater than threshold, µ is significantly smaller, indicating that phase-slip (amplitude fluctuations) is (are) necessary for a correct physical description.