Unconventional magnetic ferroelectricity in the quadruple perovskite NaMn7O12

摘要: By means of magnetic, specific heat, and pyroelectric measurements, we report on magnetic ferroelectricity in the quadruple perovskite $\mathrm{Na}{\mathrm{Mn}}_{7}{\mathrm{O}}_{12}$, characterized by a canted antiferromagnetic (AFM) CE structure. Surprisingly, is concomitant to dramatic broadening hysteresis loop, well below AFM ordering temperature. This unconventional behavior shows that formation ferroelectric domains induced symmetric exchange interaction local scale, e.g., at domain boundaries or defects. The value electric polarization, $P=0.027\phantom{\rule{4pt}{0ex}}\ensuremath{\mu}\mathrm{C}\phantom{\rule{0.16em}{0ex}}{\mathrm{cm}}^{\ensuremath{-}2}$, measured polycrystalline samples comparatively large as compared other multiferroics, suggesting above scenario promising indeed for rational design practical multiferroic materials.