Magnetoelectric coupling driven by inverse magnetostriction in multiferroic BiMn3Mn4O12

Inserting both polar A and magnetic B ions in a same crystalline phase, such as A¼Bi3þ, B¼Fe3þ or Mn3þ in simple perovskites ABO3, has been successful in achieving multiferroic properties with large ferroelectric and magnetic orders. However, modest magnetoelectric couplings have been hitherto reported, thus preventing any application for future electronics. By means of neutron diffraction, we found a large uniform C-type modulation of an E-type antiferromagnetic structure of the Mn3þ ions in the quadruple perovskite BiMn3Mn4O12. A symmetry analysis indicates that this modulation is induced by the internal strain created by the polar Bi3þ ion, which gives evidence of a large magnetoelectric coupling driven by inverse magnetostriction. This modulation is indeed absent in the isomorphic and isovalent compound LaMn3Mn4O12 containing the nonpolar La3þ ion. Our analysis indicates that this coupling mechanism is effective owing to the symmetrylimited structural distortions and inhomogeneities characteristic of the quadruple perovskite structure, thus preventing the release of the strain. We conclude that internal strain is a key control parameter to achieve large magnetoelectric couplings in proper ferroelectrics