Ordered aeschynite-type polar magnets RFeWO₆ ( R=Dy , Eu, Tb, and Y): A new family of type-II multiferroics

Abstract

We report the discovery of magnetoelectric multiferroicity in a family of oxides, RFeWO₆(R = Dy , Eu, Tb, and Y) that crystallize in a polar aeschynite-type structure (Pna21) with an ordered arrangement of Fe³⁺ and W⁶⁺ ions. Magnetization and analysis of neutron-diffraction data of DyFeWO₆ reveal a commensurate noncollinear antiferromagnetic ordering of Fe³⁺ spins (TFeN∼18 K ), which induce Dy spins to order at the same temperature. A sudden change in electric polarization (Δ P) appears in all the compounds at T Fe N = 15–18 K . The electric polarization is sensitive to an applied magnetic field, and the coupling between different magnetic R -ion and Fe-ion moments suppresses the polarization to a different extent. Although the measured polarization in polycrystalline DyFeWO₆ at 3.5 K is about 3μC/m², a simple calculation of the ionic contribution to polarization with formal charges is 75 560 μC/m² and it is of the form P = ( px,0,pz) where, p x comes from magnetic ordering and p z is associated with the polar structure in the paramagnetic state. These findings open up an avenue to explore further new polar magnets with rare-earth/transition-metal ions in the ordered aeschynite-type structure.