Magnetically induced electronic ferroelectricity in half-doped manganites

TL;DR

This study demonstrates that La$_{1/2}$Ca$_{1/2}$MnO$_3$ is a multiferroic material with significant ferroelectric polarization arising from charge, orbital, and spin ordering, independent of specific structural details.

Contribution

It reveals that charge and spin ordering induce ferroelectricity in half-doped manganites, showing a large polarization from magnetic origins, regardless of structural debates.

Findings

Charge ordering and spin dimerization break inversion symmetry.

Ferroelectric polarization reaches several microC/cm^2.

Ferroelectricity persists across different structural configurations.

Abstract

Using a joint approach of density functional theory and model calculations, we demonstrate that a prototypical charge ordered half-doped manganite, La$_{1/2}$Ca$_{1/2}$MnO$_3$ is multiferroic. The combination of a peculiar charge-orbital ordering and a tendency to form spin dimers breaks inversion symmetry, leads to a ferroelectric ground-state with a polarization up to several $\mu C/cm^2$. The presence of improper ferroelectricity does not depend on hotly debated structural details of this material: in the Zener-polaron structure we find a similar dramatic ferroelectric response with a large polarization of purely magnetic origin.