Impurity effect on the inter-chain dielectric response of the CDW condensate in K0.3MoO3

We study the effect of impurity on the charge-density-wave (CDW) state via low-frequency dielectric measurements, especially for the inter-chain direction. The extremely high dielectric constant seen in non-doped K0.3MoO3 is strongly reduced by W- or V-doping, demonstrating that the three-dimensional (3D) phase rigidity is an innate characteristic of CDW condensate. In the impurity-doped K0.3MoO3, the 3D rigidity has been lost and the CDW state exhibits a different nature in which the dielectric response of CDW cannot be explained in terms of the screened phason model.