Possible origin of nonlinear conductivity and large dielectric constant in the commensurate charge-density-wave phase of 1T−TaS2

Abstract

The electric field dependence of the dielectric properties and the nonlinear conductance of $1T\text{\ensuremath{-}}{\mathrm{TaS}}_{2}$ below 50 K has been investigated. A large dielectric constant of about ${10}^{4}$ is obtained up to ${10}^{7}$ Hz, which cannot be attributed to hopping of the localized carriers alone, the collective excitations of the commensurate charge-density-wave must be another contributor. The dielectric spectra disperse slightly in our measured temperature and frequency range. At a moderate dc bias field, the real part of the dielectric constant ${\ensuremath{\epsilon}}_{1}(\ensuremath{\omega})$ decreases. We propose that the separation of bound soliton-antisoliton pairs may be a contributor to the reduction of ${\ensuremath{\epsilon}}_{1}(\ensuremath{\omega})$ and the accompanying nonlinear conductivity with increasing dc bias.