On the structural and magnetic properties of Sr-substituted LaMnO3 nanoparticles (La1-xSrxMnO3)

Abstract

In this study, nanocrystalline lanthanum strontium manganite, La1-xSrxMnO3 (x = 0.2, 0.3, 0.4, 0.5, 0.6) where Sr substitutes in La-site are synthesized by sol–gel auto-combustion technique and annealed at 800 °C for 2hr. X-ray diffraction (XRD) study reveals the formation of a single phase rhombohedral crystal structure in all the samples. The crystallite size is calculated from Scherrer formula and the Williamson-Hall plot wherein the crystallite size are found to decrease with Sr substitution. Uniform and dense morphological structure are observed in the FESEM micrographs with average particle size ranging from 30 nm to 60 nm. Magnetic properties studied by using vibrating sample magnetometer (VSM) show decrease in saturation magnetization with increase in Sr substitution which demonstrates that ferromagnetic order is weakened and magnetic disorder increases. The maximum saturation magnetization of 32.8 emu/g is observed in La0.7Sr0.3MnO3 and has the most appropriate ratio of Mn4+: Mn3+ ≈ 1 for maximum double exchange interaction. The particle size of the nanoparticles is also found to affect the magnetocrystalline anisotropy of the system and observed to be in the order of 105 erg/cm3. These ferromagnetic LSMO along with their semi-metallic behaviour may be potentially utilised in nanoscale non-volatile memory and future spintronic devices.