The studies of XANES and thermoelectric power on the stripe phase of La2-xSrxCu0.995Ζn0.005O4 at x near

• Main Authors: Shih-Chang Haung, 黃世璋
• Other Authors: Hung-Duen Yang
• Format: Others
• Language: zh-TW
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/35803582970410097031

碩士 === 國立中山大學 === 物理學系研究所 === 93 === Since discovering the anomaly of the La-based cuprates (La2-xSrxCuO4) at x~ , researches of stripe phase have been prevailing recently. Related vast experiments, like neutron scattering, Raman and infrared ray (IR) spectra, Hall effect, and magnetic susceptibility etc. have performed on this subject. These results indicate that a crossover from one- to two-dimensional charge transport happens at x~ . In this thesis, we synthesize p-type superconductors La2-xSrxCu0.995Zn0.005O4 by solid-state reaction. It has been well know there is a marked drop in Tc- x phase diagram at x~ of La2-xSrxCuO4. It is possible that this phenomenon is related to the formation of a stripe phase. The experimental work on x-ray absorption near edge spectroscopy (XANES) in La2-xSrxCuO4 and La2-x-ySrxNdyCuO4 have been done during these years in our laboratory. The results show that the absorption-spectroscopy diagrams of two systems have apparent differences in the region of upper Hubbard Band (UHB). The differences are due to that the stripe is observed in La2-x-ySrxNdyCuO4, but not in La2-xSrxCuO4. No observation of stripe phase in La2-xSrxCuO4 may be attributed to that the drop at x~ in Tc-x phase diagram of La2-xSrxCuO4 is smaller than that in La2-x-ySrxNdyCuO4. Therefore, thesis reports the comparison of spectroscopic diagram between La2-x-ySrxNdyCuO4 and La2-xSrxCu0.995Zn0.005O4, which show more a pronounced Tc-x drop than the La2-xSrxCuO4 system. Meanwhile, the effect on the thermoelectric power by the formation of stripe phase is also investigated and discussed as well.