Critical dynamics and domain motion from permittivity of the electronic ferroelectric (TMTTF)2AsF6

TL;DR

This study investigates the critical dynamics and domain wall motion in the ferroelectric organic conductor (TMTTF)2AsF6 near its charge ordering transition, revealing critical slowing-down and domain wall behavior through dielectric measurements.

Contribution

The paper provides the first detailed analysis of critical polarization dynamics and domain wall motion in (TMTTF)2AsF6 near its ferroelectric transition using dielectric spectroscopy.

Findings

Observed critical slowing-down of polarization near Tc

Identified a sharp domain wall absorption feature below Tc

Extracted anomalous power law for order parameter viscosity

Abstract

The quasi one-dimensional organic conductor (TMTTF)2AsF6 shows the charge ordering transition at Tc101K to a state of the ferroelectric Mott insulator which is still well conducting. We present and interpret the experimental data on the gigantic dielectric response in the vicinity of TCO, concentrating on the frequency dependence of the inverse $1/\epsilon$ of the complex permittivity $\epsilon=\epsilon^\prime+i\epsilon^{\prime\prime}$. Surprisingly for a ferroelectric, we could closely approach the 2nd order phase transition and to deeply reach the critical dynamics of the polarization. We could analyse the critical slowing-down when approaching Tc from both sides and to extract the anomalous power law for the frequency dependence of the order parameter viscosity. Moreover, below Tc we could extract a sharp absorption feature coming from a motion of domain walls which shows up at a frequency well below the relaxation rate.