Magneto Transport of high TCR (temperature coefficient of resistance) La2/3Ca1/3MnO3: Ag Polycrystalline Composites

摘要

We report the synthesis, (micro)structural, magneto-transport andmagnetization of polycrystalline La2/3Ca1/3MnO3:Agx composites with x = 0.0,0.1, 0.2, 0.3 and 0.4. The temperature coefficient of resistance (TCR) nearferromagnetic (FM) transition is increased significantly with addition of Ag.The FM transition temperature (TFM) is also increased slightly with Agaddition. Magneto-transport measurements revealed that magneto-resistance MR isfound to be maximum near TFM. Further the increased MR of up to 60% is seenabove 300 K for higher silver added samples in an applied field of 7 Tesla.Sharp TCR is seen near TFM with highest value of up to 15 % for Ag (0.4)sample, which is an order of magnitude higher than as for present pristinesample and best value yet reported for any polycrystalline LCMO compound.Increased TCR, TFM and significant above room temperature MR ofLa2/3Ca1/3MnO3:Agx composites is explained on the basis of improved grains sizeand connectivity with silver addition in the matrix. Better coupled FM domainsand nearly conducting grain boundaries give rise to improved physicalproperties of the La2/3Ca1/3MnO3 manganites.