Structural and magnetic characterization of the double perovskites R2NiRuO6 (R = Pr-Er): A neutron diffraction study

Novel members of the RNiRuO family of double perovskites have been prepared via a nitrate-citrate route, followed by annealing treatments in air in the 1100-1300 °C temperature range. The crystal and magnetic structures were characterized from neutron powder diffraction (NPD) data at 300 K and 2 K. All the samples are monoclinic, P2/n space group, with a √2a√2a2a unit-cell, compared to the simple perovskite a edge. Ni and Ru ions occupy distinct octahedral positions, with a certain antisite disordering. The magnetic structures are defined by the propagation vector k = 0. The magnetic moments of the Ni cations are antiparallel to the spins of the Ru sublattice; the structure can be described as ferromagnetic [011] layers antiferromagnetically (AFM) coupled to each other. For R = Ho and Er perovskites, the rare-earth moments participate in the magnetic structure: Ho cations are ordered along the direction (010) in alternate planes AFM coupled and the magnetic moments of Er are ferromagnetically ordered along the c axis.