Giant magnetoresistance of bulk polycrystalline La0.833Na0.167MnO3 with Ag2O addition

Effects of Ag addition on electrical transport and magnetic properties of La0.67Ba0.33Mn0.88Cr0.12O3

“…The small changes of M and T C indicate that the substantial substitution of Ag + for La 3+ is not happening in these compounds. Many experiments also show that there exists no substantial substitution effect in the Agadded perovskite manganites [9][10][11][12] T C for xp0:05 samples is perhaps related to the limited substitution of Ag + for La 3+ . However, this substitution is very limited, and the maximum value of substitution may be around 5% mole ratio because T C keeps on 29471 K when x increases further.…”

“…However, the presence of the grain boundaries in these polycrystalline CMR materials introduces more resistance for the electron transport, which hinders the enhancement of MR indirectly. Recently, it is found [9,10] that by adding Ag in polycrystalline CMR materials, can lead to large room temperature MR if T C of the compounds is near room temperature, as well as to reduction in the resistivity in terms of the modifications of microstructure, electrical and magnetic inhomogeneity on the grain surfaces/boundaries. Based on these achievements, we combined Ag 2 O with polycrystalline La 0.67 Ba 0.33 Mn 0.88 Cr 0.12 O 3 (LBMCO) synthesized by sol-gel method.…”

Magnetic and electrical transport properties of La0.67Ca0.33MnO3(LCMO):xZnO composites

“…Although spin-polarized tunnelling through the grain boundaries leads to high MR at low fields at a composition called the percolation threshold for the composite system, its magnitude falls off rapidly with temperature. Several workers have attempted to enhance the low temperature low field MR (LFMR) or the room temperature MR by making composites of these CMR oxides like La 0.67 Ca 0.33 MnO 3 (LCMO) or La 0.67 Sr 0.33 MnO 3 (LSMO) with secondary phases such as an insulating oxide [7][8][9][10][11], a hard ferromagnetic material [12], a soft magnetic material [13], a polymer material [14], a glass [15], a metal [16] or metal oxide [17] or with other CMR oxides [18,19]. But in every case the basic objective is to increase the height of the tunnel barrier between the neighbouring FM grains.…”

Effect of sintering temperature on electrical transport of La0.67Ca0.33MnO3 granular system with 4% CuO addition

“…Enhanced LFMR response has been observed in some manganites-based two-phase composites. The second phases include insulating oxides [5][6][7][8], hard or soft magnetic materials [9,10], metal [11] and other CMR oxides [12]. In these composites, it is believed that dilution with the second phases impedes the magnetic homogeneity near the grain boundary area, which adjusts the barrier layer and, hence, influences the tunneling process.…”