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

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.