Dynamic properties of an incommensurate charge density wave in monoclinic TaS3 at low temperatures

The permittivity of monoclinic TaS3, a quasi-one-dimensional conductor with an incommensurate charge density wave (CDW), as a function of frequency and temperature has been studied. At low temperatures and at frequencies below 1 MHz, the temperature dependence of the real part of the permittivity shows a maximum shift to lower temperatures with decreasing frequency. The temperature dependence of the relaxation time consists of two branches corresponding to macroscopic regions of CDWs with long and short relaxation times tau on the microscopic scale. With decreasing temperature, the growth of tau- for large CDW regions is faster than thermal activation and shows a tendency to diverge at a finite temperature while the growth of tau due to the relaxation on the microscopic scale is slower than the activation rate. Our results show that with decreasing temperature the m-TaS3 quasi-one-dimensional conductor goes over to a glasslike state due to the strong pinning of CDWs by randomly distributed impurities and the formation of mutually interacting solitary CDW collective excitations. (C) 1997 American Institute of Physics.