Eur. Phys. J. B 22, 335-341 (2001)
https://doi.org/10.1007/s100510170111

Complex low-frequency dielectric relaxation of the charge-density wave state in the (2.5(OCH₃)₂DCNQI)₂Li

¹ Institute of Physics, PO Box 304, 10001 Zagreb, Croatia
² Faculty of Civil Engineering, University of Maribor, 2000 Maribor, Slovenia
³ Physikalisches Institut, Universität Stuttgart, 70550 Stuttgart, Germany

Corresponding author: ^a mpinter@ifs.hr

Received: 10 November 2000
Revised: 11 June 2001
Published online: 15 August 2001

Abstract

We report a detailed characterization of an unique 2- and 4-fold commensurate charge density wave (CDW) state in single crystals of the organic conductor (2.5(OCH₃)₂DCNQI)₂Li by means of low-frequency (0.1 Hz-1 MHz) dielectric spectroscopy. We show that in addition to the narrow Debye-like relaxation mode of strength Δε≈10⁷ with Arrhenius-like resistive decay, associated with long wavelength phason excitations, a new mode of weaker strength Δε≈10⁶ appears below 40 K and broadens with decrease in temperature. Below 25 K the mean relaxation time of the new mode saturates, whereas the Debye mode continues gradual slowing down with weaker temperature dependence, again similar to the DC conductivity. We attribute the new process to short wavelength CDW excitations that become dominant once the free carrier density is substantially reduced at low temperatures.