Enhanced ferroelectric polarization by induced Dy spin-order in   multiferroic DyMnO3
  Neutron powder diffraction and single crystal x-ray resonant magnetic scattering measurements suggest that Dy plays an active role in enhancing the ferroelectric polarization in multiferroic DyMnO3 above TNDy = 6.5 K. We observe the evolution of an incommensurate ordering of Dy moments with the same periodicity as the Mn spiral ordering. It closely tracks the evolution of the ferroelectric polarization which reaches a maximum value of 0.2 muC/m^2. Below TNDy, where Dy spins order commensurately, the polarization decreases to values similar for those of TbMnO3. 
O. Prokhnenko, R. Feyerherm, E. Dudzik, S. Landsgesell, N. Aliouane,   L.C. Chapon, and D. N. Argyriou