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    Electrical Transport and Magnetoresistance of La0.67Ca0.33MnO3: Agx (x=0, 0.1, 0.2, 0.3, 0.4) Composites
    (Korean Magnetics Soc, 2012) Gencer, H.; Pektas, M.; Babur, Y.; Kolat, V. S.; Izgi, T.; Atalay, S.
    The structural, magnetic and magnetotransport properties of La0.67Ca0.33MnO3: Ag-x (x = 0, 0.1, 0.2, 0.3 and 0.4) composites were investigated systematically. X-ray and EDX analysis indicated that Ag is not substituted into the main La0.67Ca0.33MnO3 phase and remains an additive to the second phase at the grain boundary. The Curie temperature first decreased from 269 K for x = 0 to 257 K for x = 0.1 and then remained nearly unchanged with increasing Ag content. For the x > 0.1 samples, a second transition temperature (T-M12) was observed in the resistance curves. At temperatures below 150 K, a significant enhancement in MR was observed while high temperature MR decreased with increasing Ag content. The maximum MR was observed to be 55% in the x = 0.4 sample at 10 K and a 6T magnetic field, this value is larger than that of pure La0.67Ca0.33MnO3 (53% at 265 K and 6 T). In addition, at low fields (H < 1T), a sharp increase in the MR was observed.
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    LaBaMnO films produced by dip-coating on a quartz substrate
    (Elsevier Science Sa, 2008) Gencer, H.; Gunes, M.; Goktas, A.; Babur, Y.; Mutlu, H. I.; Atalay, S.
    The electrical transport and magnetoresistance properties of the polycrystalline La0.67Ba0.33MnO3 film produced on a quartz substrate were investigated first time. X-ray powder diffraction indicated that film sample has perovskite structure. Scanning electron microscope indicated that La0.67Ba0.33MnO3 film thickness is approximately 20 mu m and the average grain size of this sample varies between 8 and 10 mu m. La0.67Ba0.33MnO3 film showed a phase transition from paramagnetic to ferromagnetic at (Tc) 130 K and a metal-insulator transition at (T-MI) 137 K at 2 mT magnetic field. The upturn of the resistance observed at low temperatures (<49 K) was attributed to the Coulomb blockade and the strong structural disorder due to the large lattice mismatch and strain relaxation. A large magnetoresistance ratio (MR(%)) of 230% was observed at 125 K and 6 T magnetic fields. (C) 2007 Elsevier B.V. All rights reserved.