拓樸超導體是凝態物理領域中的一種熱門新穎材料，並可透過數種異質結構(heterostructure)來實現，例如Fe鐵磁性(ferromagnetic)原子鍊在超導Pb(110)表面上。為了朝這個目標前進，我們成長了兩種異質結構系統: Fe/Ni Kagome/Pb(111)和 FeTe/Bi2Te3，並使用掃描穿隧顯微鏡（STM）探測其性質。
在Fe/Ni Kagome/Pb(111)系統中，磁性雜質Fe微量摻雜於s波超導體Ni Kagome/Pb(111)上，Fe原子帶有的自旋與庫柏對的交互作用引發了Yu-Shiba-Rusinov束縛態。我們使用超導探針量測此系統的掃描穿隧能譜(STS)及空間微分電導圖，雖然團隊的前屆碩士生林子軒曾使用普通導體探針研究此系統，超導探針的量測具有高能量解析度的效果，能更清楚地解析出存在於超導能隙內的特徵。然而，因為超導探針自身的狀態密度(density of states)會進入到STS訊號中， STS數據並不直接關聯到樣品的狀態密度，故我們也針對STS進行反卷積，從中提取樣品自身的狀態密度。
在第二個主題，我們將磁性原子Fe鍍在3D拓樸絕緣體Bi2Te3並形成FeTe薄膜，研究具有六方(hexagonal)形態、條紋(stripe)形態疊紋圖樣(Morié pattern)的兩種FeTe薄膜的原子結構、磁性及超導性。在超導性方面，我們確認了0.32K溫度下六方形態和條紋形態兩種薄膜皆不具有超導。而在磁性方面，我們在條紋形態FeTe薄膜使用多種不同自旋極化方向的探針，觀察到了原子尺度的條紋變化，這說明這種薄膜可能具有反鐵磁結構；我們同樣使用有自旋極化的探針量測六方形態FeTe薄膜，然而並沒有觀察到地形特徵發生變化，因此該薄膜可能為非磁性或鐵磁性。

Topological superconductor is one of popular novel materials in the field of condensed matter physics, which can be produced through several kinds of heterostructures, such as a ferromagnetic Fe chain on a superconducting Pb(110) surface. In order to achieve this goal, we have grown two types of heterostructure systems: Fe/Ni Kagome/Pb(111) and FeTe/Bi2Te3, and investigated their properties by scanning tunneling microscopy (STM).

In the Fe/Ni Kagome/Pb(111) system, a small amount of magnetic impurity Fe is doped on the s-wave superconductor Ni Kagome/Pb(111). The interaction between spins of Fe atoms and Cooper pairs leads to the emergence of Yu-Shiba-Rusinov (YSR) states. We have measured the scanning tunneling spectroscopy (STS) and spatially resolved conductance maps of this system with superconducting STM probe. Although the previous student, Tzu-Hsuan Lin, had investigated this system by normal conductor probe, the measurements with superconducting probe provides high energy resolution, which result in more detailed features appearing within the superconducting gap. But, the STS data taken with superconducting probe would not be simply related to the density of state (DOS) of the sample because the superconducting probe will contribute its own superconducting DOS into the STS signal. Therefore, I also performed deconvolution on STS data to extract the sample's own DOS.

For the second topic, we deposited magnetic atoms Fe on 3D topological insulator Bi2Te3 to form FeTe thin films, and studied the atomic structure, magnetism and superconductivity of two types of FeTe thin films with hexagonal and stripe phase Moiré patterns. Regarding superconductivity, we confirmed that neither the hexagonal nor the stripe phase films exhibited superconductivity at the temperature of 0.32K. In terms of magnetism, we observed atomic-scale pattern change in the stripe phase FeTe films using probes with different spin polarization directions, which implies a possible antiferromagnetic feature of the stripe phase FeTe. We also measured the hexagonal FeTe film using a spin-polarized probe, but did not observe any change in topographic images. The result suggest that hexagonal FeTe thin film might be non-magnetic or ferromagnetic.

摘要 i
Abstract ii
致謝 iv
目錄 v
圖目錄 vii
表目錄 xii
第一章 簡介
1.1 研究動機-----------------------------p.1
1.2 超導體-------------------------------p.2
1.3 Yu-Shiba-Rusinov 束縛態--------------p.4
1.4 拓樸---------------------------------p.6
1.5 Fe/Ni Kagome/Pb(111)相關文獻回顧-----p.8
1.6 FeTe/Bi2Te3相關文獻回顧--------------p.13
第二章 實驗儀器與原理
2.1 真空系統-----------------------------p.16
2.1.1 真空定義與性質---------------------p.16
2.1.2 真空幫浦---------------------------p.18
2.1.3 真空壓力計-------------------------p.21
2.2 電子束蒸鍍槍-------------------------p.23
2.3 掃描穿隧式電子顯微鏡------------------p.24
2.3.1 量子穿隧效應-----------------------p.24
2.3.2 Tersoff-Hamann近似-----------------p.26
2.3.3 掃描穿隧能譜-----------------------p.28
2.3.4 超導探針---------------------------p.30
2.3.5 STM工作原理------------------------p.32
2.3.6 自旋極化之穿隧效應------------------p.36
2.4 He-3低温製冷循環系統------------------p.39
第三章 實驗結果與討論
3.1 Fe/Ni Kagome/Pb(111)-----------------p.42
3.1.1 製備方法----------------------------p.42
3.1.2 Fe/ Ni-Kagome/ Pb(111)實驗結果與討論-p.44
3.2 FeTe/ Bi2Te3-------------------------p.54
3.2.1 製備方法----------------------------p.54
3.2.2 FeTe/ Bi2Te3實驗結果與討論----------p.57
第四章 結論--------------------------------p.71
參考資料-----------------------------------p.72
Appendix----------------------------------p.76

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