本文用X光吸收近邊緣結構(XANES)光譜來分析材料的空軌域電子組態，期望能將LCMO和LBMO薄膜因基板應變效應造成Tp和TC改變的情形加以解釋。將吸收光譜的實驗結果與能態密度的理論計算相比較，於是發現當LCMO薄膜受伸張應變而Tp和TC大幅下降時，O 2p與La 5d/ Ca 3d和La 6s/ Ca 4sp/ Mn 4sp混成也會大大地變弱；當LBMO薄膜受壓縮應變而Tp和TC小幅上升時，O 2p與La 5d/ Ba 5d和La 6s/ Ba 6sp/ Mn 4sp混成則是微小地變強；同時O 2p和Mn 3d混成均無改變。這表示以往將焦點放在MnO6八面體的變形上所提出的理論並不完全正確，在討論應變效應時，鑭錳氧化物La1-xAxMnO3中的La和A與O的混成才是主要關鍵。

The strain effect on La0.67Ca0.33MnO3 and La0.8Ba0.2MnO3 thin films on SrTiO3 (001) substrate with different thicknesses has been studied by X-ray absorption near edge spectroscopy (XANES), which can reveal the details of the coupling between cations and anions. The strain may suppress the TC of LCMO films while enhancing that of LBMO films. The theoretical calculation results suggest the unoccupied states of the third structure of XANES are formed by much more complex hybridization of O 2p to Mn 4sp, La 6s and (Ca 4sp or Ba 6sp) orbitals. The change of the absorption intensity of the second and third structures is compatible to the TC change of both films due to the strain effect. This strongly suggests that the strain effect on LCMO and LBMO thin films is mainly associated with the bonding situation between O and La(Ca or Ba) ions.

第一章 簡介..............................................1
第二章 龐磁阻錳氧化物應變效應相關研究回顧................3
2-1 龐磁阻錳氧化物簡介................................3
2-2 應變效應(strain effect) ...............................5
2-3 LaXCa1-XMnO3和LaXBa1-XMnO3材料介紹...............6
2-4 Orbital stability model ...............................11
第三章 X光吸收光譜(XAS)理論及實驗方法..................13
3-1 X光吸收光譜的概念...............................13
3-2 X光吸收近邊緣結構(XANES) ......................18
3-3 延伸X光吸收精細結構(EXAFS) .....................20
3-4 同步幅射實驗設備及光譜量測方式...................24
第四章 實驗儀器及量測原理...............................29
4-1 薄膜成長設備-射頻磁控濺鍍系統....................29
4-2 晶體結構分析-雙晶體X光繞射儀....................31
4-3 電性量測系統.....................................33
4-4 磁性量測-超導量子干涉儀..........................34
第五章 實驗結果與討論...................................36
5-1 La0.67Ca0.33MnO3和La0.8Ba0.2MnO3薄膜製備............36
5-2 薄膜晶格結構分析.................................39
5-3 薄膜電性分析.....................................41
5-4 薄膜磁性分析.....................................42
5-5 X光近邊緣吸收光譜數據處理.......................43
5-6 La0.75Ca0.25MnO3 ab-initial能帶計算與X光光譜之比較...47
第六章 結論.............................................48
參考文獻.................................................49
附錄
附錄一 La0.67Ca0.33MnO3和La0.8Ba0.2MnO3薄膜X光光譜量測總表
附錄二 Electron binding energies
附錄三 樣品一之O K-edge和Mn L-edge的XANES
附錄四 樣品二之O K-edge和Mn L-edge的XANES
附錄五 樣品四之Ca L-edge(LCMO)與O K-edge(LBMO)的XANES

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