Soft x-ray resonant scattering at the Ni L 2,3 edges is used to test models of magnetic-and orbital-ordering below the metal-insulator transition in NdNiO 3 . The large branching ratio of the L 3 to L 2 intensities of the (1/2 0 1/2) reflection and the observed azimuthal angle and polarization dependence originates form a non-collinear magnetic structure. The absence of an orbital signal and the non-collinear magnetic structure show that the nickelates are materials for which orbital ordering is absent at the metal-insulator transition.

Using high-resolution neutron diffraction measurements for Mn-rich hexagonal Mn-Fe-P-Si compounds, we show that the substitution of Mn for Fe on the 3f sites results in a linear decrease of the Fe/Mn(3f ) magnetic moments, while the Mn(3g) magnetic moments remain constant. With increasing temperature, the Mn(3g) magnetic moments show almost no change, while the Fe/Mn(3f ) moments decrease quickly when the transition temperature is approached. The reduction of the magnetic moments at the transition temperature and in the high-temperature range is discussed based on changes in interatomic distances and lattice parameters and high-temperature magnetic-susceptibility measurement.

Soft x-ray resonant magnetic diffraction at the Nd M edges was performed on a NdNiO 3 epitaxial film to investigate the magnetic ordering of the Nd ions below the metal-insulator transition. A noncollinear magnetic structure induced by the Ni magnetic moments best describes the azimuthal angle dependency of the ͑1 / 2,0,1/2͒ reflection. This confirms the Ni spin structure observed with soft x-ray diffraction experiments performed at the Ni L edge, providing further evidence of charge disproportionation without orbital order below the metal-insulator transition in NdNiO 3 .