Pyroelectric current and field-dependent specific heat measurements on polycrystalline samples of the quadruple perovskite (LaMn3)Mn4O12 give evidence of ferroelectricity driven by the canted antiferromagnetic ordering of the B-site Mn3+ ions at TN,B=78 K with record large remnant electric polarization up to 0.56 μC cm−2. X-ray diffraction measurements indicate an anomalous behavior of the monoclinic β angle at TN,B, which suggests that the polarization lies in the ac-plane, where the moments are collinear, and that symmetric exchange striction is the mechanism of spin-driven ferroelectricity. Polarization values up to ∼3–6 μC cm−2 are expected in single crystals or epitaxial films, which would enable the development of practical multiferroic applications.

By means of magnetic, specific heat and pyroelectric measurements, we report on magnetic ferroelectricity in the quadruple perovskite NaMn7O12, characterized by a canted antiferromagnetic (AFM) CE structure. Surprisingly, ferroelectricity is concomitant to a dramatic broadening of the magnetic hysteresis loop, well below the AFM ordering temperature. This unconventional behavior shows that the formation of ferroelectric domains is induced by the symmetric exchange interaction in the local scale, e.g. at magnetic domain boundaries or defects. The large electric polarization, P = 0.027µC cm −2 , measured in polycrystalline samples suggests that the above scenario is very promising indeed for the rational design of practical multiferroic materials.

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