NARROW-BAND NOISE AND DAMPING IN NBSE3

We report the results of a Narrow-band ''Noise'' (NBN) study, in NbSe3 for magnetic fields up to 19 T and temperatures as low as 15 K. The f irst result of this NBN study is the observation of the decrease of dJ (CDW)/dv with decreasing temperatures for both transitions. We report also new values for the absolute value dJ(CDW)/dv for both transitions , and the existence of a curvature of dJ(CDW)/dv versus frequency, in low frequency range. We have interpreted the decrease of dJCDW/dv with temperatures in terms Of Artemenko's theory which has been used in 19 84 to explain the non-linear Hall effect in TaS3. The total longitudin al current is given by J(T) = J(CDW)(1-A) + sigma1E, where the therm - AJ(CDW) is a backward normal current flow due to the moving CDW. From the saturing value of dE/dv obtained in high electric field we have de duced the total damping parameter tau-1 which is decreasing with tempe rature. Using data obtained under application of a magnetic field of 7 T and the Wonneberger's theory for the ac response of the collective mode, we have deduced the thermal variation of the bare phason damping coefficient tau0(-1). We report that for T < 30K, tua0(-1) approximat ely AT4.5 very close to the theoretical predictions of Takada, Wong an d Holstein.