Interplay between static and dynamic polar correlations in relaxor Pb(Mg_{1/3}Nb_{2/3})O_{3}

TL;DR

This study investigates the static and dynamic polar nanoregions in relaxor Pb(Mg$_{1/3}$Nb$_{2/3}$)O$_{3}$ using neutron scattering, revealing temperature-dependent behaviors linked to dielectric properties and supporting random field models.

Contribution

It provides detailed neutron scattering analysis of static and dynamic polar nanoregions in PMN, connecting microscopic dynamics with macroscopic dielectric behavior.

Findings

Static component appears at ~400 K

Dynamic component freezes at ~200 K

Dynamic intensity peaks near dielectric maximum at T$_{max}$

Abstract

We have characterized the dynamics of the polar nanoregions in Pb(Mg$_{1/3}$Nb$_{2/3}$)O$_{3}$ (PMN) through high-resolution neutron backscattering and spin-echo measurements of the diffuse scattering cross section. We find that the diffuse scattering intensity consists of \emph{both} static and dynamic components. The static component first appears at the Curie temperature $\Theta \sim 400$ K, while the dynamic component freezes completely at the temperature T$_{f} \sim 200$ K; together, these components account for all of the observed spectral weight contributing to the diffuse scattering cross section. The integrated intensity of the dynamic component peaks near the temperature at which the frequency-dependent dielectric constant reaches a maximum (T$_{max}$) when measured at 1 GHz, i. e. on a timescale of $\sim 1$ ns. Our neutron scattering results can thus be directly related to dielectric and infra-red measurements of the polar nanoregions. Finally, the global temperature dependence of the diffuse scattering can be understood in terms of just two temperature scales, which is consistent with random field models.