The Electrical Transport And Magnetization Measuring System And Magnetization Behavior Of (La_1-x Bi_x )_0.67 Ca_0.33 MnO₃

In this paper, the science and technology of the pulsed high magnetic field are introduced. Based on the pulsed high magnetic field and low temperature system, we desigened the magnetization measurement and electrical transport measurement holders.At the same time, a digital filter was developed to deal with this measuring noise problem..Using the designed system, the magnetization characteristics of (La_1-xBi_x)_0.67Ca_0.33MnO₃ was measured. The thesis mainly contains following contents: First of all, an overview of the science and technology of pulsed high magnetic field and the base structure of pulsed high magnetic field was described.Secondly, the basic theory on magnetization measurements and electrical transport measurements were systematic introduced. At the same time, because there are a lot of high-frequency noises mixed into the signals due to the outside interference in the process of signal transmission, a new digital filter was developed.Thirdly, the crystal structure of vanadium and the corresponding properties were studied, including the metal-insulator transition,spin induced G-type to C-type transition and so on.Finally, the magnetic properties of (La_1-xBi_x)_0.67Ca_0.33MnO₃ was measured, the saturated magnetization was changed with magnetic field in different doping level and different temperature, an obvious hysteresis phenomenon was observed in the manganites with higher doping level.