Nanoparticle size effect on the magnetic and transport properties of (La0.7Sr0.3)0.9Mn1.1O3 manganites

Magnetic and transport thermal measurements of nanosize (La0.7Sr0.3)0.9Mn1.1O3 manganite are reported. The nanoparticles are synthesized with use of the co-precipitation method at different (800, 900, and 950°C) temperatures. Their crystal structure is determined to be perovskite-like with a rhombohedral distortion (the space group R3¯c). The phase composition and specific surface nanopowders are determined. The average size of synthesized nanoparticles (from 40to100nm) is estimated by both the method of low-temperature adsorption of argon and x-ray diffraction measurements. All the nanosize samples show ferromagnetic-like ordering with close phase transition temperatures. Their magnetization decreases with decreasing particle size. Comparison of experimental and calculated temperature dependences of the spontaneous magnetic moment shows that the spontaneous magnetization both in magnetic field and without field is well described in the framework of the double exchange model. The decrease of the magnetiza...