XANES studies on the stripe phase of La2-xSrxCuO4 and La1.4-xSrxNd0.6CuO4 at x near 1/8
The x~ 1/8anomaly in the La-based cuprates had been puzzling since the discovery of high-Tc superconductors. Recently, the stripe phase which has attracted considerable attention in connection with many experiments, like neutron scattering, Raman and infrared(IR) spectra, Hall effect, thermoelectric power and magnetic susceptibility, etc. These results indicate that a crossover from one- to two-dimensional charge transfer accurs at x~1/8 .
In this thesis, we synthesize two series of p-type superconductors La2-xSrxCuO4 and La1.4-xSrxNd0.6CuO4 by solid-state reaction. It has been well known that there is a marked drop in Tc - x phase diagram at x~1/8 in both systems. It is possible that this phenomenon is related to the stripe phase.
This interesting question has motivated us to initiate the experiment of x-ray absorption near edge spectroscopy (XANES) to investigate the possibility of the electronic structure change caused by the stripe phase. It is found that the spectral weight of the hole carriers scales with the doping level x rather than with Tc . However, the charge stripe was observed in La1.4-xSrxNd0.6CuO4, but not in La2-xSrxCuO4. Our results also suggest that the formation of the stripe phase is not related to the structural phase transition in La1.4-xSrxNd0.6CuO4 consistent with earlier results. Comparisons are made between our results and those reported on the basic of the stripe phase scenario.
Advisor:Hung-Duen Yang; Chia-Jyi Liu; Hsiung Chou; Jiunn-Yuan Lin
School:National Sun Yat-Sen University
School Location:China - Taiwan
Source Type:Master's Thesis
Keywords:xanes stripe phase
Date of Publication:06/28/2003