Short-range cation and spin ordering in the relaxor ferromagnet La3Ni2SbO9 studied by polarized-neutron scattering and Monte-Carlo methods

摘要

Spin-polarised neutron scattering experiments have facilitated the separation of the nuclear and magnetic diffuse scattering from the partially-ordered cation distribution in the perovskite La3Ni2SbO9. The nuclear component of the data collected at 110 and 175 K could be modelled using Monte-Carlo methods when it was assumed that the distribution of Ni2+ and Sb5+ cations over their shared six-coordinate site is that which minimises the repulsive interactions between Sb5+ cations similar to 5.5 angstrom apart. Analysis of the diffuse magnetic scattering showed that nearest-neighbour and next-nearest neighbour spins show short-range antiferromagnetic and ferromagnetic coupling, respectively, at 110 K. The former persists to 175 K but the latter weakens with increasing temperature.