Structural and Magnetic Properties of La0.7Sr0.3Mn1−xNixO3 (x ≤ 0.4)

We have studied the structural and magnetic properties of La0.7Sr0.3Mn1−xNixO3 (x = 0.05, 0.1, 0.20, 0.30, and 0.40) perovskites using x-ray and neutron diffraction and magnetic measurements. Our data consist of neutron (λ = 1.479 Å) and x-ray (λ = 1.5481 Å; Cu Kα) powder diffraction and magnetization measurements. We previously suggested these systems transition from ferromagnetic to antiferromagnetic ordering with the intermediate concentrations containing coexisting domains of ferromagnetically and antiferromagnetically ordered states. Upon further detailed examination, we find that the samples are homogeneous and that neutron data can be fitted to a single long-range magnetically ordered state. The compositional dependent changes are driven by a shift in the dominant near neighbor interaction from ferromagnetic to antiferromagnetic. In the intermediate compositions, peaks previously identified as due to antiferromagnetic ordering, in fact arise from charge ordering; the system remains in a ferromagnetic state where the Ni moments are antiparallel to the Mn moments. This interpretation supersedes multiphase and spin glass models for these complex systems.