Design of a Mott Multiferroic from a Non-Magnetic Polar Metal

TL;DR

This paper predicts a new high-temperature multiferroic material by engineering electronic correlations in a polar metal, combining density-functional and dynamical mean-field theories.

Contribution

It introduces a novel approach to create multiferroics from non-magnetic polar metals using superlattice engineering and electronic correlation tuning.

Findings

Superlattice of LiOsO3 and LiNbO3 exhibits multiferroic properties.

Predicted high Curie temperature of 927 K and Néeel temperature of 671 K.

Electronic correlations can induce magnetic insulating states in polar metals.

Abstract

We examine the electronic properties of newly discovered "ferroelectric" metal LiOsO$_3$ combining density-functional and dynamical mean-field theories. We show that the material is close to a Mott transition and that electronic correlations can be tuned to engineer a Mott multiferroic state in 1/1 superlattice of LiOsO$_3$ and LiNbO$_3$. We use electronic structure calculations to predict that the (LiOsO$_3$)$_1$/(LiNbO$_3$)$_1$ superlattice is a type-I multiferroic material with a ferrolectric polarization of 41.2~$\mu$C cm$^{-2}$, Curie temperature of 927\,K, and N\'eel temperature of 671\,K. Our results support a route towards high-temperature multiferroics, \emph{i.e.}, driving non-magnetic \emph{polar metals} into correlated insulating magnetic states.