Nature of short-range ferromagnetic ordered state above T_(C) in double perovskite La_(2)NiMnO_(6)

摘要

Magnetic measurements of La_(2)NiMnO_(6) reveal that its inverse susceptibility exhibits an upward derivation from Curie-Weiss behavior above T_(C), indicating the presence of a short-range ferromagnetic ordered state. It is suggested that the upward derivation is due to antiferromagnetic interactions arising from anitisite defects, which is supported by the magnetic studies on the samples where the antiferromagnetic interactions are modulated by partially doping La with Sr or by decreasing the sample size. Basing on these results, we propose that the short-range ferromagnetic ordering is induced by antisite defects against long-range ferromagnetic ordering of the Ni/Mn sublattice.