Commensurate Dy magnetic ordering associated with incommensurate lattice distortion in multiferroic DyMnO3

Synchrotron x ray diffraction and resonant magnetic scattering experiments on a single crystal of orthorhombic DyMnO3 have been carried out between 4 and 40 K. Below TN Dy 5 K, the Dy magnetic moments order in a commensurate structure with propagation vector 0.5 b . Simultaneous with the Dy magnetic ordering, an incommensurate lattice modulation with propagation vector 0.905 b evolves while the original Mn induced modulation is suppressed and shifts from 0.78 b to 0.81 b . This points to a strong interference of Mn and Dy induced structural distortion