Narrow-band 'noise' and damping in NbSe ₃

WE report the results of a Narrow-band 'Noise' (NBN) study, in NbSe ₃ for magnetic fields up to 19 T and temperatures as low as 15 K. The first 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 decreases of dJ _CDW/dv with temperatures in terms of Artemenko's theory which has been used in 1984 to explain the non-linear Hall effect in TaS ₃. The total longitudinal current is given by J _T = J _CDW(1-A)+sigma ₁E, where the therm AJ _CDW is a backward normal current flow due to the moving CDW. From the saturating value of dE/dv obtained in high electric field we have deduced the total damping parameter τ ¹ which is decreasing with temperatures. 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 τ _O ^-1. We report that for T<30K, τ _O ^-1≈AT ^4.5very close to the theoretical predictions of Takada, Wong and Holstein.