Influence of Sintering Temperature on Low-field Spin-polarized Tunneling Magnetoresistance of La0.7Ca0.3MnO3

Abstract

In this study we report the effect of sintering temperature on the low field magnetoresistance (LFMR) of La_0.7Ca_0.3MnO₃ manganite synthesized through sol-gel technique. The La_0.7Ca_0.3MnO₃ has been sintered at 600°C, 700°C, 800°C, 900°C and 1200°C. The crystallite as well as particle size also show strong dependence on the sintering temperature. While the ferromagnetic – paramagnetic (FM-PM) transition temperature remains almost constant, the metal – insulation transition temperature drop gradual and the low field magnetoresistance (LFMR) increase with a decrease in grain size. We have analyzed our data based on the spin – polarized transport of conduction electrons at the grain boundaries.