The commensurate phase of multiferroic HoMn2O5 studied by X-ray magnetic   scattering
  The commensurate phase of multiferroic HoMn2O5 was studied by X-ray magnetic scattering, both off resonance and in resonant conditions at the Ho-L3 edge. Below 40 K, magnetic ordering at the Ho sites is induced by the main Mn magnetic order parameter, and its temperature dependence is well accounted for by a simple Curie-Weiss susceptibility model. A lattice distortion of periodicity twice that of the magnetic order is also evidenced. Azimuthal scans confirm the model of the magnetic structure recently refined from neutron diffraction data for both Mn and Ho sites, indicating that the two sublattices interact via magnetic superexchange. 
G. Beutier, A. Bombardi, C. Vecchini, P.G. Radaelli, S. Park, S-W.   Cheong, L.C. Chapon