The Preparation And Doping Of Strong Spin-orbit-coupling Sr₂IrO₄ Compound

The 5d transition metal oxides(TMO) are believed to be weak ly-correlated wide band systems due to the extended nature and weak Coulomb interactions of the electrons. However, novel physics would be induced by the strong spin orbital coupling(SOC), together with its competition with other interactions such as Coulomb interaction. O ne typ ical phenomenon is the Mott insulator in Ir oxides induced by SOC. The AIrO-214 compounds, with A=Sr or Ba, are similar to the parent compounds of cuprate LaC uO-214 phase in many aspects. The theoretical calculation predicts that the exotic unconventional superconductivity could be realized through carrier doping in these systems. Therefore, it is very important to search for unconventional superconductivity in these SOC-induced Mott insulators, which may open a new area of superconductivity.In this dissertation, the technique conditions of the conventional solid-state reaction method are explored to prepare the pure phase Sr2IrO4 polycrystalline, and the samples are successfully prepared. Different samples are prepared by changing grinding time, calcinatio n time and calcination temperature. The samples are characterized b y means of X-ray diffraction(XRD), scanning electron microscopy(SEM) and Energy Dispersive X-ray Spectrometer(EDS). Through the characterization analysis, the optimal preparation technique of pure phase Sr2IrO4 samples has been obtained. It is shown by XRD, SEM and EDS analysis that the pure phase Sr2IrO4 sample with high crystallinity, regular particle shape and uniform particle distribution can be prepared by this optimal preparation technique.This thesis also focus on the influence o n the structure of Sr2IrO4 compound with partial substitution of Sr site by La to carry out electron doping in this system. T he prepared samples Sr2-xLaxIrO4(x≤0.3) are characterized by XRD, SEM, EDS, Rietveld structure refinement and Raman spectrum and the effects are analyzed of electron doping by element substitution on the crystal structure of Sr2IrO4 compound. According to experimental results, the crystal structure of Sr2IrO4 compound is changed by electron doping. Lattice contraction and weakened distortion of IrO6 octahedron is confirmed by Rietveld structure refinement and Raman spectrum. In order to explore the dependence of the crystal structure of doped Sr2IrO4 on tempeture, Sr1.8La0.2IrO4 sample is characterized by Raman spectrum at different temperatures.