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The structural, magnetic and electronic properties of the polycrystalline La1−xAgxMnO3 are systematically investigated as a function of Ag-doping level. The result of the Rietveld refinement of X-ray powder diffraction shows that the samples are single rhombohedral (R3¯C) structure phase for x<0.2. For x&ges;0.2, the samples are composed of a R3¯C perovskite phase and a nonmagnetic metal Ag phase. The temperature dependence of resistivity shows that all samples undergo a sharp insulator–metal (I–M) transition accompanying a paramagnetic to ferromagnetic transition with the decrease of temperature. However, for x<0.2, an obvious double I–M transition with a single ferromagnetic transition is observed. In the meanwhile, a large magnetoresistance (MR) with low applied magnetic field is observed. The electronic and magnetic inhomogeneity induced by Ag doping and the nonmagnetic metal Ag phase are presented to account for the transport properties and large MR in these compounds. [Copyright &y& Elsevier]

Abstract: The magnetic properties of single crystal have been studied by dc magnetization and magnetotransport data. The ferromagnetic (FM) to paramagnetic (PM) transition temperature and the metal–insulator transition temperature are 177 and 194K, respectively. The deviation of the inverse susceptibility from the Curie–Weiss law indicates the presence of a Griffiths-like phase in this system, viz., an inverse susceptibility characterized by with and close to the 177K. The slopes of vs. isotherms are negative between 300 and 194K and positive above 300K and below 194K. The transition cannot be regarded as first or second order on the basis of the Banerjee criterion. The above interesting and complex magnetic transition is a manifestation of competition between the double exchange mechanism and correlations arising from coupled spin and lattice degrees of freedom present in studied system. To analyze the magnetism around , the critical behavior of is investigated based on the data of static magnetization measurements. It is seen that the critical behavior of belongs to the mean-field model and shows a second-order like magnetic transition at high fields, however, the poor scaling is found toward low fields, which suggest that the critical behavior is related to the observed complicated magnetic transition. The possible origin of observed complex FM state has been discussed based on the competition between the charge/orbital order clusters and the A site disorder. [Copyright &y& Elsevier]

Abstract: La0.7Sr0.3MnO3 nanoparticles were prepared by a simple chemical coprecipitation route. Structural, magnetoresistance (MR), and magnetic properties were investigated. Rietveld refinement of X-ray powder diffraction result shows that the sample is single-phase with the space group of R3¯C. The result of field-emission scanning electronic microscopy shows that most of the grain sizes are distributed from 50 to 200nm. The composition determined by energy-dispersive spectroscopy is the stoichiometry of La0.7Sr0.3MnO3. The ferromagnetic to paramagnetic transition is sharp with Curie temperature T C=367K, which further confirms that the sample is single-phase. The steep change in MR at low fields is attributed to the alignment of the magnetization, while the high-field MR is due to the grain boundary effect. [Copyright &y& Elsevier]

Abstract: La0.7Sr0.3MnO3 (LSMO) and SrFe12O19 (SFO) samples were synthesized by chemical coprecipitation method. The composites of (1− x)LSMO:xSFO (x is mass%) were prepared using solid-state cosintering. The microstructure, electrical transport, and magnetic properties of the derived composites were systematically investigated. Compared with pure LSMO, the enhancement of low-field magnetoresistance (LFMR) is observed in the composites. The magnetoresistance (MR) value at 300K for the sample with x =0.05 is about 2.9 times larger than that of the pure LSMO. The enhanced MR was attributed to the enhanced spin-dependent intergrain tunneling at the interfaces and grain boundaries due to the enhanced magnetic disorders and antiferromagnetic (AFM) couplings near boundaries between LSMO and SFO grains. [Copyright &y& Elsevier]

Abstract: Polycrystalline and epitaxial La0.7Sr0.3MnO3 (LSMO) thin films are fabricated by chemical solution deposition (CSD) method on Si (100) and LaAlO3 (100) single crystal substrates, respectively. The transport and magnetic properties of the films are investigated. The magnetoresistance (MR) of LSMO films fabricated on Si (100) substrates is largely enhanced at low temperatures compared with that of LSMO films on LaAlO3 substrates. The difference of MR properties is discussed in terms of grain boundary (GB) effects. [Copyright &y& Elsevier]

Abstract: La0.8Na0.2MnO3 films were successfully fabricated via the chemical solution deposition (CSD) method on LaAlO3 and YSZ single crystal substrates. The results showed that the two samples behaved like epitaxial films. It was suggested that it was possible to fabricate highly (h00)-oriented colossal magnetoresistance films on YSZ substrates using CSD. [Copyright &y& Elsevier]

Abstract: Polycrystalline La0.7Sr0.3MnO3 (LSMO) thin films with nanometer scale grains were fabricated on Si (100) single crystal substrates by the chemical solution deposition (CSD) method. The LSMO film exhibits typical transport properties of the polycrystalline film of manganites. The low-field magnetoresistance (MR) as high as 2.54% is obtained at and 300K. The enhanced MR effect for LSMO film is attributed to the suppression of the spin-dependent scattering of polarized electrons at the grain boundaries (GBs). [Copyright &y& Elsevier]