Study On Structure, Magnetic Property Of (La_2/3Ba_1/3)(Cu_0.15Mn_0.85O₃) Thin Film And La_0.7-xNd_xSr_0.3MnO₃

A series of La_2/3Ba_1/3Cu_0.15Mn_0.85O₃ thin films on Si(100)substrates have been grown by RF magnetron sputtering.The phase structure,microstructure,surface chemical states and magnetic property of the thin films have been measured by using of XRD,STM,XPS and VSM.The results show that the orthogonal perovskite structure is formed at 750℃and is perfact complete phase structure is found at 900℃. As increasing of the annealing temperature,the grains size become larger,and oxygen vacancies between the particles gradually disappear.Furthermore,Due to increasing of the lattice oxygen,it was found that the magnetoresistance increased rapidly.The series of manganite perovskite polycrystalline samples of La_0.7-xNd_xSr_0.3MnO₃(x=0,0.05,0.10,0.15,0.2) were prepared by solid state reaction in the air.Some properties such as the phase structure,microstructure, magnetic property of the samples have been measured by using of XRD,SEM,etc. The results show that the crystal cell volume decrease gradually with the increasing concentration of the Nd ions.The more of the doping Nd ions content are,the smaller of the grains size is.In all sample,the La_0.7Sr_0.3MnO₃ samples grain size is most large. The samples' infrared absorption spectra have been measured at room temperature and all samples appear the absorption peak in the range of 574～602cm^-1.The peak moves from higher frequency to lower frequency along with the doping ionic Contents Increasing.Magnetic property survey that the doping RE ions Contents and magnetism regulation have important effect on magnetoresistance(MR) of the sample.