Soft Phonon Anomalies in Relaxor Ferroelectrics

TL;DR

This paper reviews the discovery and analysis of phonon anomalies called 'waterfalls' in relaxor ferroelectrics, linking them to polar micro-regions through neutron scattering and a coupled-mode model.

Contribution

It provides a comprehensive review of waterfall phonon anomalies in relaxor ferroelectrics and introduces a coupled-mode model explaining their origin.

Findings

Identification of waterfall phonon anomalies in relaxor ferroelectrics.

Successful application of a coupled-mode model to describe these anomalies.

Linking phonon anomalies to polar micro-regions.

Abstract

A review is given of the phonon anomalies, which have been termed ``waterfalls,'' that were recently discovered through a series of neutron inelastic scattering measurements on the lead-oxide relaxor systems PZN-xPT, PMN, and PZN. We discuss a simple coupled-mode model that has been used successfully to describe the basic features of the waterfall, and which relates this unusual feature to the presence of polar micro-regions.