Role of grain size on the magnetic properties of La0.7Sr0.3MnO3

Nanophasic La0.7Sr0.3MnO3 samples were synthesized using the citrate-gel method. The samples were annealed at different temperatures ranging from 600 to 1200 °C. Grain size was observed to increase with the increase in annealing temperature. Furthermore, the magnetization data of these samples show well defined hysteresis. Saturation magnetization was observed to increase with increase in particle size. This gives evidence of formation of a magnetically dead layer at the surface. The thickness of the dead layer has also been calculated. The coercivity of nanoparticles follows the same trend as predicted theoretically and particles below 22 nm are found to be single domain. The ferromagnetic to paramagnetic transition temperature also increases with increase in particle size.

► Synthesis of nanocrystalline La0.7Sr0.3MnO3 by the citrate-gel method.
► Saturation magnetization increases with increase in particle size.
► Formation of dead magnetic layer.