Multiple-valued electric polarization in multiferroic GdMn2O5 from first principles

Abstract We reported in this Letter the high-temperature (high-T) lattice stability and low-temperature (low-T) multiferroicity of GdMn2O5 by performing first-principles density functional theory (DFT) calculations. We show that the high-T paramagnetic structure should be denoted as an uncommon superparaelectric state, and that the low-T multiferroic phase shows a multiple-valued electric polarization depending on the combination of spin order and high-T polar structure. It is the multiple-valued polarization in the low-T phase that leads to an unusual tunability of multiferroicity in GdMn2O5 by the electric-poling-sequence. In addition, our results demonstrate the dominant role of Mn-Mn exchange striction in determining the large type-II multiferroicity, while the effect of Gd-Mn exchange striction is small. Our present work may offer an effective strategy for superior magnetoelectric effects in type-II multiferroics.