EFFECT OF QUENCHING RATE ON SDW DYNAMICS IN (TMTSF)2CLO4

The pinning mechanism of SDW condensate associated with the imperfect nesting effect was investigated with the measurement of the temperatur e dependence of the threshold electric field E(T) for the depinning of SDW in (TMTSF)2ClO4 for various anion quenching rates. The relatively strong temperature dependence of E(T) observed in the most rapidly qu enched phase with T(C)=5.85 K is described by the 3-dimensional impuri ty weak pinning. With decreasing the quenching rate, the temperature d ependence of ET becomes gradual for T(C) >3 K. This behavior is explai ned by the change of pinning mechanism to the strong pinning. For much lower quenching rate (T(C)<3 K), the temperature dependence of ET bec omes steeper again and is attributed to the increase of imperfectness of nesting of Fermi surface. It is understood that the SDW pinning is provided by the disordered array of anion.