本論文主要研究超導與鐵磁超晶格結構之物理特性，期望在一般特性外能藉由界面的交互作用引致三態超導的出現。我們利用脈衝雷射沉積系統來製備樣品。首先由成長單層釔鋇銅氧(YBa2Cu3O7, YBCO)超導薄膜及鑭鍶錳氧(La0.7Sr0.3MnO3, LSMO)鐵磁薄膜開始，確認最佳成長條件下可以得到YBCO之超導轉換溫度為90K，而LSMO之鐵磁轉換溫度為355K；同時兩薄膜的平整度控制在最低狀況(~1nm)。在此良好的基礎下進行磊晶堆疊成長。超晶格薄膜之特性經由X光反射率(XRR)及X光繞射(XRD)量測結構特性，使用穿透式電子顯微鏡觀查測樣品結構特性以及剖面之微結構。結果表示，成功成長[YBCO／LSMO]2超晶格結構。然而原子力顯微鏡顯示樣品表面仍出現一些大顆粒之析出物，除此之外，其他區域則非常平坦，均方根粗糙度(rms)約1nm。此外改良本實驗室之變溫電性量測系統以及與林思廷和陳伯昱同學合作重寫自動控制程式，以最佳之條件搭配電磁鐵量測其電傳導特性。結果顯示上層之LSMO層嚴重影響YBCO層之吸氧能力，導致TC下降，以及在低溫下未觀察到明顯三態超導之特性。不過超導臨界電流值(IC)-外磁場(H)之曲線在低磁場有一轉折趨勢，似乎有可能為三態超導之現象，但仍需更多實驗數據及理論模擬方能在未來了解三態超導能的物理機制。

In this thesis, the physical properties of LSMO/YBCO super lattices were studied. Our goal is by using the exotic interface coupling to generate triplet superconductivity at interface. We used pulsed laser deposition (PLD) systems to grow multilayer structures. To search the best growth conditions each layer and the multilayer structure are defined according to their phase transition and surface topography. The result shows that the best TC,on of the YBCO film is 90K, and TP of the LSMO film is 355K. When LSMO/YBCO grow into superstructures, X-ray Reflection (XRR)、X-ray Diffraction (XRD)、and Transmission Electron Microscopy (TEM) were employed to study the crystal structure and interface properties. Results show that the YBCO and LSMO were successfully grown into superstructure. The atomic force microscope (AFM) investigation shows some big particles scattering over on top of a very flat surface of a roughness of 1nm. With help of my classmate 林思廷and 陳伯昱, we modified electric measurement software and found that the multilayer structure slowing down the oxygen up-taken ability of YBCO layer and results in lower TC. Unfortunately, we didn’t observe the triplet state superconductivity, but there is a transition at low magnetic field in the IC-H Curve, which indicates possible emerging of triplet superconductivity. More studies in experiments and theory modeling are needed to understand the intriguing physics of triplet superconductivity.

論文審定書 i
誌 謝 ii
摘 要 iii
Abstract iv
目 錄 v
圖 次 vii
第一章 前言、文獻回顧 1
1-1 前言 1
1-2 文獻回顧 2
第二章 基本理論 4
2-1 磁性物質的簡介 [20-22] 4
2-1-1 順磁性(paramagnetic) 4
2-1-2 鐵磁性(ferromagnetic) 5
2-1-3 反鐵磁性(anti-ferromagnetic) 6
2-1-4 亞鐵磁性(ferrimagnetic) 6
2-1-5 抗磁性(diamagnetic) 7
2-2 超導體的簡介 7
2-2-1零電阻 8
2-2-2抗磁性(Meissner effect) 8
2-2-3第一類超導體與第二類超導體 9
2-2-4 BCS理論 10
2-3-1 YBa2Cu3O7-x材料介紹 12
2-3-2 釔鋇銅氧的傳導機制 13
2-4 單態超導與三態超導 15
第三章 實驗方法及量測系統 17
3-1 YBa2Cu3O7-x靶材製作 17
3-2 SrTiO3基板清洗 20
3-3 薄膜成長 21
3-4 脈衝式雷射沉積系統(Pulse Laser Deposition, PLD) 23
3-5 X光繞射儀 (X-Ray Diffraction system) 25
3-6 原子力顯微鏡(Atomic Force Microscopy, AFM) 28
3-7 穿透式電子顯微鏡 (Transmission Electron Microscope, TEM) 29
3-8 電性量測系統 31
第四章 實驗結果與討論 32
4-1 YBCO 靶材晶體結構及導電特性 32
4-2 YBCO 薄膜電性分析 33
4-3 YBCO 表面形貌分析(AFM) 37
4-4 LSMO 薄膜電性與結構分析 40
4-5 LSMO/YBCO 多層膜晶體結構繞射分析 (XRD) 41
4-6 LSMO/YBCO 多層膜結構分析 (XRR) 43
4-7 LSMO/YBCO 多層膜表面形貌分析 (AFM) 44
4-8 LSMO/YBCO 穿隧式電子顯微鏡分析 (TEM) 46
4-9 LSMO/YBCO多層膜電性分析 (R-T、I-V) 49
4-10 LSMO/YBCO 多層膜磁性量測 (SQUID) 56
第五章 結論 59
參考資料 60

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