Electronic correlations decimate the ferroelectric polarization of multiferroic HoMn2O5

TL;DR

This study demonstrates that electronic correlations significantly reduce the ferroelectric polarization in multiferroic HoMn2O5, aligning theoretical predictions with experimental observations by considering strong Coulomb interactions.

Contribution

It introduces ab initio calculations including Coulomb interactions to explain the suppression of polarization in HoMn2O5, revealing the microscopic cancellation mechanism.

Findings

Electronic correlations decimate ferroelectric polarization.

Computed polarization matches experimental values.

Microscopic cancellation between ionic and electronic contributions.

Abstract

We show that electronic correlations decimate the intrinsic ferroelectric polarization of the recently discovered class of multiferroic manganites RMn$_2$O$_5$, where R is a rare earth element. Such is manifest from {\it ab initio} bandstructure computations that account for the strong local Coulomb interactions between the manganese 3d electrons --the root of magnetism in these materials. When including these the computed electronic, magnetic and lattice structure of multiferroic HoMn$_2$O$_5$ results in an amplitude and direction of polarization that is in accordance with experiment. The microscopic mechanism behind the decimation is a near cancellation of the ionic polarization induced by ferroelectric lattice displacements and the electronic one caused by valence charge redistributions.