Field-induced Characteristics Of Doped Manganese Oxides

Mixed-valence-doped manganese perovskites with the general formula R_1-xA_xMnO₃ (where R and A are rare- and alkaline-earth ions, respectively) are the typically strongly correlated electron systems. Since the R_1-xA_xMnO₃ films exhibit the colossal magneto-resistance effect and field sensitivity, they have wide potential applications in the field of information technique. The colossal magneto-resistance appears at temperature close to the Curie temperature, and resistance will reduce with the temperature being increased or decreased quickly. La_1-xA_xMnO₃(A=Ca, Sr, Ba) materials have the Curie temperature near room temperature, which promotes the research and development of this material systems, and in recent years becomes a very interested area in condensed matter physics and materials science.More systematic study on La_1-xA_xMnO₃ and the main contents of the thesis are as follows:1. The poly-crystal sample La_2/3A_1/3MnO₃ (A=Ca, Sr, Ba), La_0.9Sr_0.1MnO₃ were prepared by Solid Reaction, and the thin films of La_2/3A_1/3MnO)3 (A=Ca, Sr, Ba) ,La_0.9Sr_0.1MnO₃ were deposited by direct-magnetron sputtering. The samples were characterized by the X-ray and Atom Force Microscope.2. The thickness of the films of La_2/3A_1/3MnO₃ (A=Ca, Sr, Ba) was measured from the elliptic spectrum, and the refractive index of the films was calculated, and also the bandwidth was estimated.3. The electricity, magnetic, optical characteristics of La_0.9Sr_0.1MnO₃ thin film was researched and the results are simply explained from phase-separation.4. The film La_2/3Ca_1/3MnO₃/SrTiO₃/ La_2/3Ca_1/3MnO₃ was fabricated and the properties were studied.