Interface induced giant magnetoelectric coupling in multiferroic superlattices

TL;DR

This study reveals a giant magnetoelectric coupling in BaTiO3/CaMnO3 superlattices, where electric polarization is strongly affected by magnetic spin configurations, due to interface-induced suppression of specific lattice modes.

Contribution

First-principles calculations demonstrate a significant interface-induced magnetoelectric coupling in multiferroic superlattices, highlighting the role of lattice mode suppression.

Findings

Electric polarization in CaMnO3 layers is comparable to BaTiO3 layers.

Switching from antiferromagnetic to ferromagnetic nearly doubles polarization.

Giant magnetoelectric coupling arises from interface effects suppressing antiferrodistortive modes.

Abstract

The electric and magnetic properties of (BaTiO$_3$)$_n$/(CaMnO$_3$)$_n$ short-period superlattices are studied by the first-principles calculations. The local electric polarizations in the CaMnO$_3$ layers are significant, comparable to that in the BaTiO$_3$ layers. Remarkably, the electric polarization is almost doubled when the spin configuration changes from antiferromagnetic to ferromagnetic in the superlattices, indicating a giant magnetoelectric coupling. This enhancement of the magnetoelectric coupling is due to the suppression of the antiferrodistortive mode in the CaMnO$_3$ layers at the interfaces.