Magnetic properties of double perovskite La2BMnO6 (B = Ni or Co) nanoparticles

Abstract

Double perovskite La₂BMnO₆ (B = Ni and Co) nanoparticles with average particle size of ∼50 nm were synthesized using a facile, environmentally friendly, and scalable molten-salt reaction at 700 °C in air. Their structural and morphological properties were characterized by X-ray diffraction and transmission electron microscopy. Their magnetic properties were evaluated and compared using dc magnetic M–T and M–H, and ac magnetic susceptibility versus frequency, temperature, and field for the first time. The dc magnetization curves show paramagnetic–ferromagnetic transitions at T_C ∼ 275 and 220 K for La₂NiMnO₆ (LNMO) and La₂CoMnO₆ (LCMO) nanoparticles, respectively. ac susceptibility revealed that the LCMO nanoparticles had a single magnetic transition indicative of Co²⁺–O²⁻–Mn⁴⁺ ordering, whereas the LNMO nanoparticles showed more complex magnetic behaviors suggesting a re-entrant spin glass.