Studies on the high-temperature ferroelectric transition of multiferroic hexagonal manganite RMnO3

TL;DR

This study investigates the ferroelectric transition in hexagonal manganite RMnO3, revealing it as a single, abrupt transition driven by R-Op displacement, with implications for understanding multiferroic domain physics.

Contribution

It provides new insights into the high-temperature ferroelectric transition mechanism in RMnO3 using high-temperature X-ray diffraction.

Findings

Ferroelectric transition is a single, abrupt transition.

R-Op displacement is the primary order parameter.

Transition involves MnO5 tilting and polarization development.

Abstract

Hexagonal manganites are multiferroic materials with two highly-dissimilar phase transitions: a ferroelectric transition (from P63/mmc to P63cm) at a temperature higher than 1000 K and an antiferromagnetic transition at TN=65 - 130 K. Despite its critical relevance to the intriguing ferroelectric domain physics, the details of the ferroelectric transition are yet not well known to date primarily because of the ultra-high transition temperature. Using high-temperature X-ray diffraction experiments, we show that the ferroelectric transition is a single transition of abrupt order and R-Op displacement is the primary order parameter. This structural transition is then simultaneously accompanied by MnO5 tilting and the subsequent development of electric polarization.