Magnetic Properties of Interacting La0.67Sr0.33MnO3 Nanoparticles

Magnetic nanoparticles of La0.67Sr0.33MnO3 (LSMO) with mean particle sizes of 13, 16, 18, and 21 nm were prepared by the sol-gel method. The samples were characterized by X-ray diffraction (XRD) using Rietveld refinement and transmission electron microscope (TEM). Fourier transform infrared (FTIR) transmission spectroscopy revealed that stretching and bending modes are influenced by annealing temperature. Dc magnetization versus magnetic field of the samples was carried out at room temperature. Magnetic dynamics of the samples was studied by the measurement of ac magnetic susceptibility versus temperature at different frequencies and ac magnetic fields. A frequency-dependent peak was observed in ac magnetic susceptibility versus temperature which is well described by Vogel-Fulcher and critical slowing down laws, and empirical and parameters. By fitting the experimental data with Vogel-Fulcher magnetic anisotropy energy and an effective magnetic anisotropy constant have been estimated. The obtained values support the presence of strong interaction between magnetic nanoparticles of LSMO.