| 摘要: | 本論文主要是利用軟X光共振散射來探討在La2-xSrxNiO4中電子自旋所形成的調制結構（spin stripes）。由於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光共振散射技術來增加磁結構的散射訊號。實驗中利用入射光在Ni L3,2-edge所產生的共振效應來增加來自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Ni電子在3d軌域的電子結構。樣品La2-xSrxNiO4（x=1/3）的電子自旋調制結構波向量為Qso ≈（0.67, 0, 0），而 x=0.4為 Qso≈（0.63, 0, 0），針對這兩個波向量利用X光的二向性，即水平線偏振光與垂直線偏振光，來探討磁結構的方向性，另外實驗中也利用兩個不同摻雜量的樣品來比較當摻雜不同比例的Sr時其3d軌域電子結構的態密度變化及晶格場分裂情形。
We report the study of the doping effect on the electric structure of La2-xSrxNiO4 (Nickelat) using resonant soft x-ray scattering. Nickelat is iso-structure with the high-Tc superconductor cuprate（LSCO）. With the hole doping on the parent material La2NiO4, nickelate changes its electronic structures, and forms spin-ordering and charge-ordering at low temperatures. As x-rays are not sensitive to spins, we applied resonant x-ray scattering to enhance the reflection intensity. When the incident x-ray energies are in the vicinity of Ni–L2,3 absorption edges, the intensity of charge- and spin-ordering peak were observed largely increased. The wave vector of spin stripes in La2-xSrxNiO4 is Qso≈（0.67, 0, 0）for x=1/3 and Qso≈（0.63, 0, 0）for x=0.4. By the use of polarization analyses, we can study the polarization dependence of spin stripes. In addition, we also compare the density of state in 3d orbital and crystal field splitting with different hole concentration |
