Effect of Second Introduced Phase on Magnetic and Magnetotransport Properties of (1-x)La_(0.7)Sr_(0.3)Mn_(0.9)Co_(0.1)O_3/x Ag (x=0, 2, 4) Nanocomposites

摘要

The structural, magnetic and magnetotransport properties of (l-x)La_(0.7)Sr_(0.3)Mn_(0.9)Co_(0.1)O_3(LSMCO)/x% Ag (x=0%, 2%, 4%) nanocomposites were investigated to explore the role of second introduced phase. (1 -x) LSMCO/x% Ag (x=0%, 2%, 4%) nanocomposites are prepared via solid-state reaction method. X-ray diffraction (XRD) and SEM analysis indicated that x% of Ag are not substituted into the main LSMCO phase and remains an additive to the second phase at grain boundaries [1]. The structural parameters and the reliability factors for all the samples were successfully determined by the Rietveld refinement. Magnetization and transport properties of (l-x)LSMCO/x% Ag nanocomposites have been reported. Resistivity of the composite samples increases with Ag content in comparison with the pure LSMCO, and suppressed with applied magnetic field in all the composite samples [2]. The metal-insulator transition (T_(MI)) and accompanied paramagnetic-ferromagnetic transition (T_c) temperatures decrease with increase in Ag content. The electrical resistivity of the experimental results is explored by theoretical model below T_(MI). The maximum MR was observed to be 55% in the x=4% sample at 5 K temperature under 7 T magnetic field, this value is larger than that of pure LSMCO (19% at 5 K and 7 T), which is encouraging for practical application. Summarily, the addition of Ag in LSMCO improves MR% values significantly due to the more grain boundary contribution and result in better physical properties of the parent manganite system.