Evidence of charge-density-wave fluctuations in the low frequency optical conductivity of K0.3MoO3and (TaSe4)2I

Abstract

Abstract The low temperature charge-density-wave (CDW) ground state has been extensively studied in the model quasi one-dimensional compounds K0.3MoO3 (blue bronze) and (TaSe4)2I. Below the Peierls transition temperature T 3D (183 K and 263 K in blue bronze and (TaSe4)2I, respectively) the conduction electrons exhibit long-range, three-dimensional order, and the interesting low temperature properties, including the pinned mode resonance and bound phonon states, have been clearly established. In contrast, the high temperature metallic state in these compounds has not been characterized nearly as extensively. In this paper we present the results of optical conductivity measurements performed above T 3D in the millimeter and submillimeter frequency range which, when combined with higher frequency infrared to ultraviolet reflectivity measurements, show clear deviations from simple metallic behavior. Futhermore, the pronounced excitations which appear in the spectra below 50 cm−1 for the electric field E polar...