Multiferroic properties and metal-to-insulator transition in hexagonal oxides*

ABO₃-type oxides that include the rare-earth ferrites and manganites (RFeO₃, RMnO₃ with R=Lu, Y, etc.) and crystallize in a hexagonal structure with layered trigonal bipyramid BO₅ polyhedrons are often improper ferroelectrics with unique magnetic properties and also exhibit linear magnetoelectricity. In this work, we have investigated the effects of electron doping on LuFeO₃ to stabilize ferro- and ferri-magnetic states similar to that observed in (LuFeO₃)_m/(LuFe₂O₄)₁ superlattices [Nature 537.7621 (2016): 523-527]. We then explicitly achieve these magnetic states with real chemical alloying. Our results indicate that the doping can lead to two magnetic sublattices with spin differentiation in the Fe cations, which breaks the symmetry and alters the 120^o canting of the Fe spins observed in the parent compound. Based on the presence of polar distortions in the structure, electric-field-control of magnetic differentiation, ordering and metal-to-insulator transition may be possible in these systems, which can lead to novel applications.