Engineering charge ordering into multiferroicity

TL;DR

This paper proposes a novel superlattice design strategy to engineer charge ordering into multiferroic materials, demonstrated with a LaFeO3/LaTiO3 model, resulting in a material exhibiting both ferroelectricity and ferrimagnetism.

Contribution

Introducing a superlattice approach that combines charge ordering and spacing layers to create new multiferroic materials with large polarization and magnetic order.

Findings

Charge ordering combined with spacing layers breaks inversion symmetry.

The LaFeO3/LaTiO3 superlattice exhibits multiferroic properties.

The approach can be generalized to design other multiferroic structures.

Abstract

Multiferroic materials have attracted great interests but are rare in nature. In many transitional metal oxides, charge ordering and magnetic ordering coexist, so that a method of engineering charge-ordered materials into ferroelectric materials would lead to a large class of multiferroic materials. We propose a strategy for designing new ferroelectric or even multiferroic materials by inserting a spacing layer into each two layers of charge-ordered materials and artificially making a superlattice. One example of the model demonstrated here is the perovskite (LaFeO$_3$)$_2$/LaTiO$_3$ (111) superlattice, in which the LaTiO$_3$ layer acts as the donor and the spacing layer, and the LaFeO$_3$ layer is half doped and performs charge ordering. The collaboration of the charge ordering and the spacing layer breaks the space inversion symmetry, resulting in a large ferroelectric polarization. As the charge ordering also leads to a ferrimagnetic structure, the (LaFeO$_3$)$_2$/LaTiO$_3$ is multiferroic. It is expected that this work can encourage the designing and experimentally implementation of a large class of multiferroic structures with novel properties.