Classification and Interpretation of the Polarization of MultiferroicRMn2O5

Abstract

We have collected and compared temperature-dependent polarization data of multiferroic R Mn 2 O 5 for 11 kinds of rare earths ( R ) from the literature and our own measurements. Although the reported data are inconsistent, it was found that the maximum polarization values for R =Y, Dy, Ho, Er, and Tm are almost equal above 30 K except for the phase transition temperature where the polarization disappears. The findings suggest a standard polarization value for R Mn 2 O 5 of 100–120 nC/cm 2 at 30 K in a commensurate magnetic (CM) phase. We discuss the nature and issues of the measured polarization of R Mn 2 O 5 from the data and our detailed measurement results for YMn 2 O 5 . Temperature-dependent ferroelectric hysteresis loops of YMn 2 O 5 by the double-wave method reveal that an antiferroelectric-like high-temperature incommensurate magnetic (ICM) phase and a ferroelectric low-temperature ICM phase, while the intermediate CM phase is ferrielectric.