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 (TNFe ∼ 18 K), which induce Dy spins to order at the same temperature. A sudden change in electric polarization (P) appears in all the compounds at TNFe = 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 3 μC/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, px comes from magnetic ordering and pz 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.
(a) Results of Rietveld refinement of neutron-diffraction data of DyFeWO6 collected at 3.5 K. The first row of vertical bars represents the nuclear Bragg positions, and the second row represents magnetic Bragg peak positions. (b) The magnetic structure of DyFeWO6.
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