臺灣博碩士論文加值系統

來由過渡金屬氧化物所組成的鈣鈦礦結構超晶格吸引了很多注意力。由高溫超導體和半金屬鐵磁材料這二個矛盾的自然特性的材料所組成的超晶格是最令人興奮的例子之一。電荷和電子軌道在介面的重新分布對於了解不尋常的鄰近效應(proximity effect)和巨觀的磁性質是很重要的。這種奈米結構為研究新的強電子關聯現象提供了一個獨特的舞台且對於開發自旋電子學裝置擁有巨大的應用潛力。這篇論文使用軟Ｘ光共振散射技術來研究長在SrTiO3 (001) 方向基板上的YBa2Cu3O7/La2/3Ca1/3MnO3超晶格。這塊超晶格使用脈衝雷射鍍膜技術製作。我們使用Ｘ光繞射以及X光反射率的技術來確認樣品的結構和膜厚，並提供了證據顯示此超晶格確實是磊晶成長。從軟Ｘ光共振散射實驗結果的分析指出，可能有電子從LCMO層移轉到YBCO層的電荷移轉的現象在此超晶格的介面發生

Recently superlattice of pervoskite transition-metal oxides layers has attracted much attention. A superlattice made of high-temperature superconductor and half-metal ferromagnet (HTSC/FM) represents one of the most exciting examples because of their mutually incompatible order parameters. The charge redistribution and orbital occupancy at interfaces are important for understanding the proximity effect and macroscopy magnetic properties. Those nanostructures present a unique playground for new physical phenomena associated with strongly correlated electrons systems and possible technological application in the field of spintronics. Here we performed the measurements of soft x-ray scattering (RSXS) on a YBa2Cu3O7/La2/3Ca1/3MnO3 (YBCO/LCMO) superlattice grown by the pulsed laser deposition (PLD) method on a SrTiO3 (STO)-(001) oriented substrate. The epitaxial growth of the superlattice was characterized with x-ray diffraction. The observed oscillation of soft x-ray reflectivity indicates the high quality of the artificial superlattice structure. The results of RSXS indicated that there could be charge transfer from LCMO layers to YBCO layers at the interface.

1 Introduction 1
1.1 Overview.............................................1
1.2 YBa2Cu3O7 and La2/3Ca1/3MnO3 ....................... 4
2 Film Growth and Characterization ......................6
2.1 Film Growth by Pulsed Laser Deposition ............. 6
2.2 Characterization by Hard X-ray .................... 12
2.2.1 X-ray Reflectivity .............................. 14
2.2.2 X-ray Diffraction ............................... 18
2.3 Summary ........................................... 22
3 Experiment Techniques and Setup
3.1 Resonant Soft X-ray Scattering .................... 23
3.1.1 Thomson Scattering .............................. 23
3.1.2 Resonant Scattering ............................. 25
3.1.3 Magnetic Scattering ..............................26
3.2 Experiment Setups ..................................28
3.2.1 Elliptically Polarized-Undulator Beamline ........28
3.2.2 Diffractometer....................................30
4 Resonant Soft X-Ray Scattering of YBCO/LCMO Superlattice
4.1 Phase Shift ....................................... 35
4.2 Charge Transfer at Interface .......................43
5 Conclusion ...........................................51
Appendix A The Fourth Superlattice Peak .......................52

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