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  • 學位論文

SrFeOx的電荷與電子自旋有序結構之X光散射研究

Study of the charge and spin ordering in SrFeOx using X-ray scattering

指導教授 : 杜昭宏

摘要


本論文主要是利用X光共振散射與變溫量測來探討在SrFeOx中的電荷有序(charge-ordering)與電子自旋所有序結構(spin-ordering)。由於電荷與磁結構的散射截面積非常小,所以利用一般X光繞射技術無法獲得足夠的強度來分析研究,為了能得到足夠的繞射強度,因此利用了軟X光共振散射使繞射峰強度增加。實驗中利用入射光在Fe L2,L3-edge與O K-edge所產生的共振效應來增加來自charge-ordering與spin-ordering繞射峰的散射振幅,並利用此繞射峰對能量變化的關係圖來探討Fe電子在3d軌域的電子結構。樣品 SrFeOx的電荷有序結構波向量為Qco ≈(0, 0, 0.64),而電子自旋有序結構的波向量為Qso ≈(0, 0, 0.5),針對這兩個波向量進行變溫量測觀察其結構的相變化,其結構的相變溫度分別為Tco ≈ 107K以及Tso ≈ 65K,並利用X光的二向性,即水平線偏振光與垂直線偏振光,來探討電荷結構與電子自旋的行為與方向性。

並列摘要


We report the study of charge/spin-ordering in single crystal SrFeOx using resonant soft x-ray scattering. Probing the charge and spin ordering using x-rays is difficult due mainly to the very weak diffraction intensity. However, this difficulty can be overcome by the use of resonant x-ray diffraction. In this study, we performed the resonant soft x-ray diffraction at the Fe L-edge and O K-edge, and observed a huge enhancement from the spin and charge ordering reflections. The wave vectors of charge- and spin-ordering in SrFeOx were observed to be Qco ≈ (0, 0, 0.64) and Qso ≈ (0, 0, 0.5) with transition temperatures at Tco ≈ 107 K for charge ordering and Tso ≈ 65 K for spin. These reflections were also further confirmed to originate from charges and spins, respectively, using the different polarized x-rays.

參考文獻


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