Influence of antiferromagnetic ordering on ferroelectric ordering in LuMnO3

TL;DR

This study investigates how antiferromagnetic ordering affects the dielectric properties of LuMnO3, revealing weak coupling between magnetic and electric orderings due to geometric constraints.

Contribution

It provides new insights into the weak coupling mechanism between magnetic and ferroelectric orderings in LuMnO3 through neutron diffraction analysis.

Findings

Weak magnetic-electrical coupling in LuMnO3

Dielectric anomalies near T_N caused by geometric constraints

Magnetic exchange is mainly in the ab-plane of MnO5 polyhedra

Abstract

We have studied the influence of antiferromagnetic ordering on the local dielectric moments of the MnO_5 and LuO_7 polyhedra by measuring neutron powder diffraction patterns of LuMnO_3 at temperatures near T_N. We show that the coupling is weak, because the magnetic exchange coupling is predominantly in the ab-plane of the MnO_5 trigonal bipyramids, and the electric dipole moments, originating in the LuO_7 polyhedra, are oriented along the hexagonal c-axis. Anomalies in the dielectric properties near T_N are thus caused by the geometric constraints between the MnO_5 and the LuO_7 polyhedra.