本文主要利用X光光譜探討不同形貌之矽基板對La0.7Sr0.3MnO3/Si的影響。由場效發射式掃描電子顯微鏡 (SEM) 及超導量子干涉儀 (SQUID) 之結果推測樣品晶粒尺寸的變化與其飽和磁化強度以及磁化現象有所關連。進一步藉由錳L3,2-edge以及氧K-edge近邊吸收光譜得知由氧缺陷所造成的錳二價離子以非等量的形式存在於不同形貌矽基板的常態錳三、四價樣品中。另一方面，由錳L3,2-edge邊磁圓偏振光譜中發現此錳二價離子會因為含量的不同，產生相異的磁耦合作用。藉由以上量測包含SEM, X光光譜以及磁性相關技術，推斷樣品在不同形貌矽基板中所導致不同的邊界或缺陷效應，會造成錳二價與錳三、四價離子兩者之間的含量比例在不同樣品中的差異。而此含量比例與樣品中飽和磁化強度並非呈現完全的線性關係，這暗示錳二價在樣品中會造成磁性不穩定的狀態，除了降低鐵磁性的效應, 如: 磁死層(magnetic dead layer)之外，尚存在其他影響磁耦合的因子。

This investigation of x-ray spectroscopy is focused on the series samples of La0.7Sr0.3MnO3/n+-Si with different morphology. The results of scanning electron microscope (SEM) and superconducting quantum interference device (SQUID) show that the magnetism is basically associated with the grain size of each sample. The existence of the various amount of Mn2+ between these generally Mn3+/4+-doped samples is observed by Mn L3,2-edge and O K-edge x-ray absorption near edge structure (XANES). Based on XANES, this amount of Mn2+ is strongly related to the oxygen defect. On the other hand, Mn L3,2-edge X-ray magnetic circular dichroism (XMCD) was carried out for the magnetic coupling which is sensitive to amount of Mn2+. According to the measurements above including SEM, x-ray and magnetism related techniques, the Si substrates with different morphology cause the change of Mn valence state with more or less amount of Mn2+ in each sample via the various defects or boundary conditions. However, the incompletely linear relationship between ferromagnetism and amount of Mn2+ implies that this amount of Mn2+ induces a magnetically unstable state. Except the reduction of ferromagnetic coupling, e.g. magnetic dead layer (MDL), there are still some other factors left to influence magnetic coupling.

目錄
致 謝	I
中文摘要	II
英文摘要	III
目錄	IV
圖表目錄	VI
第一章、緒論	1
第二章、X光吸收光譜簡介	4
(一)、吸收邊緣與E0值	6
(二)、 X光吸收近邊緣結構(X-ray Absorption Near Edge Structure、XANES)	7
(三)、延伸X光吸收精細結構(Extended X-ray Absorption Fine Structure、EXAFS)	8
(四)、實驗方法	13
(五)、數據分析	17
第三章、X光磁圓偏振二向性簡介 (X-ray Magnetic Circular Dichroism、XMCD)	21
(一)、理論模型	21
(二)、實驗方法	22
第四章、實驗數據分析與討論	25
(一)、樣品製備與基本量測	25
(二)、X光吸收近邊緣結構 (X-ray Absorption Near Edge Structure、XANES)之分析	31
(三)、X光磁圓二向性能譜 (X-ray Magnetic Circular         Dichroism、XMCD)之分析	38
(四)延伸X光吸收精細結構 (Extended X-ray Absorption Fine Structure、EXAFS)之分析	44
第五章、結論	46
參考文獻	47

圖表目錄
圖1-1 LSMO/ n+-Si NTs薄膜文獻之SEM表面幾何結構圖與示意圖	3
圖1-2 LSMO/Si薄膜樣品文獻之定磁場變溫磁化率	3
圖2-1光子能量與銅吸收截面關係圖	5
圖2-2 XANES與EXAFS分界圖	10
圖2-3光電子平均自由路徑與能量關係圖	10
圖2-4單一散射與多重散射之圖像
   (a)為單一散射路程示意圖 (b)為多重散射路程示意圖	11
圖2-5射出電子受鄰近原子的背向散射，而產生干涉現象
   (a)建設性干涉 (b)破壞性干涉	12
圖2-6 X光吸收光譜實驗示意圖	14
圖2-7三種光譜量測方法	16
圖2-8 X光吸收光譜之數據分析流程	17
圖 3-1 Ni L3,2-edge 吸收光譜。實線和虛線分別表示 Ni 對正磁場和負磁場的 X 光吸收光譜。	24
圖3-2 Ni L3,2-edge XMCD 譜圖	24
圖4-1 (a)、(b) LSMO 薄膜之X光繞射圖	28
圖4-2 LSMO鈣鈦礦結構圖與錳氧八面體示意圖	28
圖4-3分別為TF90、TF60以及NTs180之頂視圖(a)-(c)與側視圖(d)-(f)	29
圖4-4為LSMO/Si薄膜定磁場變溫磁化率的量測結果	30
圖4-5 LSMO/Si薄膜角度變化與標準樣品歸一化後的Mn K-edge XANES	32
圖4-6 LSMO/Si薄膜與標準樣品歸一化後的TEY Mn L3,2-edge XANES	33
圖4-7 LSMO/Si薄膜與置放在空氣中兩個月歸一化後的Mn L3,2-edge XANES	35
圖4-8 (a)室溫之 LSMO/Si薄膜O K-edge TFY，(b)Si基板O K-edge TFY，(c)高斯峰擬合O 2p之未佔據態與Mn 3d之混成軌域與面積的積分	37
圖4-9 (a) T=300K下LSMO/Si薄膜在正負磁場下之Mn L3,2-edge及XMCD譜圖	40
圖4-9 (b) T=80K下LSMO/Si薄膜在正負磁場下之Mn L3,2-edge及XMCD譜圖	41
圖4-10為TEY Mn L3-edge以MnO與LSMO(Bulk)擬合Mn2+在各樣品中所佔的百分比	42
表4-1 LSMO/Si薄膜TEY之Mn價數與XMCD強度之百分比	43
圖4-11 LSMO/Si薄膜與放置空氣中一個月定磁場變溫磁化率量測	43 
圖4-12 Mn K-edge EXAFS傅立葉轉換圖	45

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