The spectral, structural and transport properties of the pseudogap system (TaSe 4 ) 2 I

Abstract

Abstract.The room temperature "metallic" properties of the quasi-one-dimensional material (TaSe 4 ) 2 I differ markedly from those expected of either a Fermi or a Luttinger Liquid, showing strong signs of a suppression of the density of states at the Fermi level. We present evidence for the existence of strong quasi-static fluctuations of structural order with long correlation length. These fluctuations produce a pseudogap in the density of states. We compute the temperature dependence of the optical and DC conductivities of (TaSe 4 ) 2 I in its conducting phase, the nature of its core hole spectra, the NMR Knight Shift and relaxation rate. Predictions for these quantities are made on the basis of a Lee, Rice and Anderson model. This model represents the simplest theory of a pseudogap, and gives satisfactory agreement with experiment in the cases where comparisons can be made. In contrast, the predictions of a strongly correlated (Luttinger Liquid) model appear to to contradict the data. The chief remaining discrepancy is that the gap deduced from transport quantities is less than that observed in photoemission. We discuss some possibilities for resolving this issue.

Optical conductivity of a quasi–one-dimensional system with fluctuating order

“…This enables us to find an extrapolation of σ 1 (ω) in the frequency regime 0 < ω 0.1. We would like to note that our results differ from perturbative results of the optical conductivity which were calculated within the same model to first order in perturbation theory without considering vertex corrections [12]. The perturbative results give a finite dc conductivity which for this model must be an artifact of perturbation theory but nevertheless explain the qualitative behavior of the dc conductivity of Peierls systems above their charge density wave transition.…”

Structure Refinement of the Semiconducting Compound Cu3TaS4from X-Ray Powder Diffraction Data

“…Ternary compounds belonging to the family Cu 3 -M-VI 4 (M = V, Nb, Ta, VI = S, Se, Te) are interesting materials due principally to their potential applications as electronic devices, especially as light-modulators [1,2]. Earlier studies on the lattice vibration in the sulfide and selenide compounds revealed that they belong to the p-type semiconductors [3][4][5].…”

Structural characterization of the ternary compound Cu3TaSe4

“…Ternary compounds belonging to the family Cu 3 MSe 4 (M = V, Nb, Ta) are interesting materials due principally to their potential applications as electronic devices, especially as lightmodulators [1][2][3][4][5][6].…”