Unraveling the impact of nonmagnetic Sc substitution on the magnetic properties of La2NiMnO6 double perovskite

Abstract

The structural, electronic, and magnetic properties of a sol-gel prepared series of La2Ni1-xScxMnO6 compounds have been extensively studied using X-ray diffraction, X-ray absorption near edge structure, and dc magnetization techniques, respectively. The entire series was isostructural and exhibited the La2NiMnO6 double perovskite P21/n monoclinic structure. The nonmagnetic Sc3+ substitution led to the evolution of competing magnetic phases in La2Ni1-xScxMnO6. The substitution also caused an increase in lattice parameters, cell volume, and bond lengths. Consequently, Sc3+ dilution resulted in a dramatic decrease in Curie temperature, suggesting a reduction in the strength of the Ni2+-O2-Mn4+ superexchange ferromagnetic interaction. The Sc3+ substitution generated antisite defects, which significantly suppressed the saturation magnetization of the system. The competing magnetic interactions observed in the La2Ni1-xScxMnO6 system are discussed in terms of cation disorder, cation valances, and changes in the bond lengths/angles, caused by the Sc3+ substitution. ©2021 IOP Publishing Ltd.