Soft chemical synthesis and transport properties of La0.7Sr0.3MnO3 granular perovskites

The thermal decomposition of a precursor complex, using ethylenediaminetetraacetic acid (EDTA) as a complexing agent, was introduced to synthesize La0.7Sr0.3MnO3 granular perovskites. The dependence of crystallization, grain size and surface morphology on calcination temperature was investigated. Spin-dependent interfacial tunneling magnetoresistance corresponding to microstructure was observed. Our results indicate that decreasing grain size leads to broadening of the ferromagnetic–paramagnetic transition and enhancement of the extrinsic magnetoresistance caused by grain boundaries. Further decrease in grain size will result in the disappearance of the metal–insulator transition and weakening of the magnetoresistance effect at room temperature.