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    Title: 利用X光共振散射研究La53Sr1/3NiO4的條紋結構
    Other Titles: Study of stripes in La5/3Sr1/3NiO4 using resonant X-ray scattering
    Authors: 吳沛芳;Wu, Pei-Fung
    Contributors: 淡江大學物理學系碩士班
    杜昭宏
    Keywords: 條紋結構;共振散射;Resonant Scattering;Stripes;La5/3Sr1/3NiO4
    Date: 2011
    Issue Date: 2011-12-28 18:06:17 (UTC+8)
    Abstract: 本論文主要是利用共振散射以分光儀來分辨出電荷以及電子自旋條紋結構,由於電荷和電子自旋條紋是發生在同一個調制結構的波向量上,因此在沒有分光儀的情況下無法將這兩種調制結構分辨出來。由於磁結構的散射截面積遠小於電荷結構的散射截面積,因此利用一般X光繞射技術無法得足夠的散射振幅,為了獲得到更強的訊號,因此利用X光共振散射技術。由La5/3Sr1/3NiO4電子自旋所產生的自旋調制結構與光偏振方向的特性,利用共振效應來增強電子自旋條紋所產生的散射振幅。而本實驗是利用Ni K-edge的共振效應來增強磁結構的散射振幅,並分析La5/3Sr1/3NiO4在Qco(2.66, 0, 1)以及Qso(3.33, 0, 2)這兩個波向量的共振訊號。由調制結構波向量與入射光能量的變化圖分析出電荷結構及磁結構的不同,並搭配磁結構與溫度的變化圖來確定磁結構的臨界相變化,進而解釋La5/3Sr1/3NiO4 隨溫度改變在L軸向產生二次轉折的原因。另外實驗在La2-xSrxNiO4(x=0.225)中利用了方位角掃描(azimuthal scan)證明出電荷調制結構的二重對稱性。
    We report the study of the electric structure and azimuthal-angle dependence of the charge and spin stripes using resonant x-ray diffraction in La2-xSrxNiO4 (Nickelat). La2-xSrxNiO4 is isostructural with high Tc superconducting cuprate La2-xSrxCuO4. With Hole-doped into the parent material, La2NiO4 changes its electric structure and forms charge and spin ordering at low temperatures. We observed satellite reflections due to the formation of charge/spin stripes in La2-xSrxNiO4 (x=0.225 and 0.33) with a wave vector Qco= (2.55, 0, 5) for x=0.225, Qco= (2.66, 0, 1) and Qso= (3.33, 0, 2) for x=0.33. Using resonant x-ray scattering, the spin ordered reflection Qso was observed to show the resonant effect. Using azimuthal scan, the charge ordering was observed to propose the character of two-fold symmetry.
    Appears in Collections:[物理學系暨研究所] 學位論文

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