Inter Comparison Of The Magneto Transport Of La2/3ca1/3mno3 : Ag/In Polycrystalline Composites

In this paper, we report the synthesis, magnetotransport features, and magnetization of polycrystalline La-2/3 Ca-1/3 MnO3:Ag-x/In-x composites with x = 0, 0.1, 0.2, 0.3 and 0.4. In the case of La2/3Ca1/3MnO3:Ag-x, the temperature coefficient of resistance (TCR) near ferromagnetic (FM) transition enhances significantly with the addition of Ag. The FM transition temperature (T-FM) is also increased slightly with Ag doping. Magnetotransport measurements revealed that magnetoresistance (MR) is found to be maximum near T-FM. Very sharp TCR is seen near T-FM with the highest value of up to 15% for an Ag (0.4) sample, which is an order of magnitude higher than for pristine sample and is the best value yet reported for any polycrystalline LCMO compound. Increased TCR, T-FM, and significant above room temperature MR of La2/3Ca1/3MnO3:Ag-x composites is explained on the basis of improved grains size. Interestingly the La2/3Ca1/3MnO3:In-x composites behaved exactly in the opposite way, resulting in decreased T-FM, and TCR compared to the pristine LCMO compound. In fact, the grains morphology of LCMO:In-x composites is seen to be inferior to pristine LCMO which is opposite of the LCMO:Ag-x case.