The Effect Of Er₂O₃Doping On The Electric-Magnetic Properties In LCMO And LCSMO System

The magnetoresistance of manganese perovskite have drawn considerable interest in recent years. People want to apply it in life and production. However, to gain a large magnetoresistance value need to apply a large magnetic field, and the temperature range is very narrow, which always limits its application. some researchers found that with a small field and wide temperature range can get very large magnetoresistance in manganites polycrystal material, which is paid more attention. The mangnetoresistance with small magnetic field is called low field magnetoresistance(LFMR)In this paper, we use manganites LCMO and LCSMO as the mother material of the composites compounding with Er₂O₃, the composites will form a polycrystal material and the magnetoresistance will be obtained due to the grain boundary. The structure, morphologies, the electrotransport, magnetoresistance and magnetic properties of the composites were studied .This paper consists of five chapters below.In the first chapter, the present study of MR material and kinds of MR effects were introduced. We take the LFMR as the emphasis. The research aim of my topic and the thinking of my choosing this title were expatiated in the end.In the second chapter, we introduce the prepare method and test technologies of the magnetoresistance material, and the physical properties of the mother material LCMO and LCSMO,and compare the two mother materials.In the third chapter, the composites of LCMO/ Er₂O₃ with different proportions were prepared. The structure, morphologies, the electro transport, magnetoresistance and magnetic properties of the composites were studied.In the forth chapter, the composites of LCSMO/ Er₂O₃ with different proportions were prepared. The structure, morphologies, the electro transport, magnetoresistance and magnetic properties of the composites were studied.The last chapter is the conclusion.