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

作者：Dyakonov V^*; Slawska Waniewska A; Kazmierczak J; Piotrowski K; Iesenchuk O; Szymczak H; Zubov E; Myronova S; Pashchenko V; Pashchenko A; Shemjakov A; Varyukhin V; Prilipko S; Mikhaylov V; Kravchenko Z; Szytula A; Bazela W

来源：Low Temperature Physics, 2009, 35(7): 568-576.

DOI：10.1063/1.3170933

Magnetic and transport thermal measurements of nanosize (La0.7Sr0.3)(0.9)Mn1.1O3 manganite are reported. The nanoparticles are synthesized with use of the co-precipitation method at different (800, 900, and 950 degrees C) temperatures. Their crystal structure is determined to be perovskite-like with a rhombohedral distortion (the space group R (3) over barc). The phase composition and specific surface nanopowders are determined. The average size of synthesized nanoparticles (from 40 to 100 nm) 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 magnetization with decreasing particle size is due to the increasing surface contribution to the magnetization. The magnetic entropy is shown to increase with increasing applied magnetic field and to be smaller for the small particles. The resistivity is found to become higher with decreasing particles size at any temperatures.

• 出版日期2009-7