Charge order in LuFe2O4: antiferroelectric ground state and coupling to magnetism

TL;DR

This study investigates the charge ordering in LuFe2O4, revealing an antiferroelectric ground state with coupling to magnetism, and highlights the temperature-dependent transition between ferroelectric and antiferroelectric states.

Contribution

It provides experimental and theoretical evidence for the charge configuration and its coupling to magnetic order in LuFe2O4, advancing understanding of multiferroic charge order.

Findings

Incommensurate charge order below 320 K with polar Fe/O double-layers.

Diffuse scattering at 360 K indicates ferroelectric short-range correlations.

Charge order and magnetism are coupled, with temperature-dependent incommensuration.

Abstract

X-ray scattering by multiferroic LuFe2O4 is reported. Below 320 K, superstructure reflections indicate an incommensurate charge order with propagation close to (1/3,1/3,3/2). The corresponding charge configuration, also found by electronic structure calculations as most stable, contains polar Fe/O double-layers with antiferroelectric stacking. Diffuse scattering at 360 K, with (1/3,1/3,0) propagation, indicates ferroelectric short-range correlations between neighboring double-layers. The temperature dependence of the incommensuration indicates that charge order and magnetism are coupled.