Electromagnetic Properties and Magnetoresistance Effects ofManganite La0.7_xYxCa0.3MnO3

This paper discusses the preparation of the manganite polycrystalline samples La0.7-xYxCa0.3MnO3 by the solid-state reaction technique. The effects that the different substitution of Y for La affects the crystal structure, electromagnetic properties and magnetoresistance effects are also studied. No peak is observed on the resistance-temperature curves(R-T curves) of the sample La0.6Y0.1Ca0.3MnO3 with the decrease of the tempeature, whereas onepeak is observed for the sample La0.5Y0.2Ca0.3MnO3, and the complex transport properties are shown. The magnetoresistance(Rm) of the two samples increases with the decrease of the temperature, but no peak is observed. The sample La0.5Y0.2Ca0.3MnO3 shows large magnetoresistance over a wide temperature range, moreover, the magnetoresistance effects strengthen with the increase of Y substituting for La from x=0.1 to x=0.2.