Colossal Magnetoresistance Effects of La_(1-x)Sr_xMnO_3

摘要

Polycrystal samples of La_(1-x)Sr_xMnO_3 (x=0.2, 0.3) have been synthesized using a sol-gel method. The effect of sintering process on the sample microstructure and Sr doping on the magnetoresistance for La_(1-x)Sr_xMnO_3 have been investigated. The results show that the increase of sintering temperature and time can promote the crystallization of samples and reduce the content of impurity. The additive of Sr makes Mn ion in materials relatively compact, and this causes the distorted deformation of the materials structure. The magnetoresistance (MR) changes with the Sr doping. When x=0.2, the maximum MR percent of sample is about 43 percent and keep about 40 percent between 10-150K. At room temperature, the MR percent will decrease to about 6.5 percent. When x = 0.3, the order magnetoresistance (OMR) effect occures above the room temperature.