Stretched-Exponential Dielectric Relaxation in a Charge-Density-Wave System

Abstract

The relaxation of the electric polarization is investigated in the charge-density-wave compound ${\mathrm{K}}_{0.3}$Mo${\mathrm{O}}_{3}$. Direct measurements of discharge current in the time interval of ${10}^{\ensuremath{-}5}$ to ${10}^{3}$ s reveal a stretched exponential law for the time decay of polarization: $P={P}_{0}\mathrm{exp}[\ensuremath{-}{{\frac{t}{\ensuremath{\tau}}(T)}}^{1\ensuremath{-}n}]$, where both the initial polarization, ${P}_{0}$, and the exponent ($1\ensuremath{-}n=0.7$) are temperature independent. The time scale of the process indicates temperature activation with an activation energy equal to the single-particle Peierls gap. The glassy relaxation of randomly pinned charge-density waves is compared with recent theories and experiments on spin-glasses.