本論文主要探討兩個題目，第一個是有關於拓樸絕緣體成長於磁性絕緣體上之介面反應與電子結構分析。利用磁性絕緣體之鄰近效應或是磁性材料摻雜可破壞拓樸表面態的時間反衍對稱性，產生許多有趣之自旋電子學現象例如異常或爾效應，而磁性材料與拓樸絕緣體之異質結構預期可在室溫觀察到此現象，並且具有較為均勻之磁場分布，擁有較為廣泛之應用度。在實驗方面，我們使用分子束磊晶矽統在銩鐵石榴石（Tm3Fe5O12，TmIG）與α相氧化鋁（α-Al2O3）上方成長硒化鉍（Bi2Se3）薄膜，接著透過自製可攜帶式高真空腔體運送樣品至同步輻射中心與工業研究院量測角解析光電子光譜，探討不同厚度之拓樸絕緣體薄膜受到磁性基板鄰近效應表現在電子結構之影響，我們觀察到成長在磁性與非磁性基板上之硒化鉍薄膜，在相同厚度3-QL（quintuple layer）的情況下，成長於磁性基板上之表面態能隙較大約26 meV，故而我們能進一步的估計出其界面交換耦合效應約9.5 meV，此異質材料結構可提供良好之平台來研究拓樸絕緣體相關之界面電子能譜現象。
第二個題目是有關於單元素拓樸材料α相錫（α-Sn）的光電子能譜分析，我們將錫成長於銻化銦（InSb）基板上，透過兩種材料不同之晶格常數使得錫受到薄膜表面方向之壓縮應力並維持在α相的晶格排列，並且在銻化銦基板上與錫薄膜之間額外成長一層銻化銦的磊晶層，來提升錫薄膜之結晶品質，而在光電子能譜實驗中，在30-BL（bilayer）厚度之α相錫中，我們也確實觀察到相較於文獻更為清晰之拓樸表面態，進一步與電子能帶計算印證之下，可將表面態與價帶分辨出來，並且第一次在價帶之外側觀察到獨特之類似表面態之能帶。接著透過調控光能量之角解析電子能譜分析分析370-BL厚度之α相錫，我們能分辨各個能帶之二維或三維表徵，在距離費米能階200 meV之束縛能位置，能觀察到拓樸表面態與價帶外側之表面態在布里淵區內不隨著kz而變化，顯示其具有二維性質，而鄰近之價帶也無拓樸半金屬之特性，故比較兩種厚度α相錫薄膜我們可歸納出其拓樸絕緣體性跟厚度無關，與之前之文獻報導在兩著厚度間有拓樸絕緣體到拓樸狄拉克班金屬之相變的結論不同。

Topological insulators (TIs) are new phases of quantum matter with unique surface states protected by time-reversal symmetry (TRS). Breaking the TRS in TIs leads to numerous exotic phenomena such as quantum anomalous Hall effect (QAHE). These novel phenomena originate from an energy gap opened at Dirac surface states by exchange interaction with magnetic elements. Magnetically doped TI was firstly reported to exhibit such an exchange gap, but the observation temperature of QAHE was smaller than 2 K because of the disorder created by magnetic dopants. Another way to break TRS is through magnetic proximity effect (MPE) in TI/magnetic insulator heterostructures with a stronger ferromagnetism and uniform interfacial magnetization.
In this work, TI Bi2Se3 thin films were grown by molecular beam epitaxy (MBE) on ferromagnetic thulium iron garnet (TmIG) with perpendicular magnetic anisotropy and high TC above 500K. The band structures of Bi2Se3/TmIG bilayers were investigated by angle-resolved photoemission spectroscopy (ARPES). Comparative thickness-dependent study in 3-6 QL Bi2Se3 grown on TmIG and sapphire was performed, where Bi2Se3 thin films in 2D regime allowed us to probe the interfacial coupling. The energy gap at Dirac surface states of 3 QL Bi2Se3/TmIG was larger than that of 3 QL Bi2Se3/sapphire(0001) by ~ 26 meV. The larger surface state gap of Bi2Se3/TmIG could be induced by MPE, on top of hybridization of the top and bottom surface states. Based on such an assumption, the interfacial exchange coupling constant of Bi2Se3/TmIG is determined to be ~ 10 meV, which was in excellent agreement with the lower bound of 7.7 meV calculated from anomalous Hall conductance. Our study demonstrated the opportunity of probing interfacial band of TI-based heterostructures.
In another work in this thesis, the elemental topological material α-Sn was grown on InSb(001) with slight in-plane compressive strain. Clear topological surface states were observed with crystallinity improvement by growing InSb epi-layer between the α-Sn and InSb substrate. Comparing the calculated band diagram, the topological surface states (TSS1, TSS2) and bulk valence band (VB) were observed in our sample. Also, the surface-state like bands (SS) outside the VB were detected for the first time. By energy dependent ARPES, the 2D/3D character of the band dispersion could be investigated. At the E-EF = -0.2 eV, the TSS1 and SS were confirmed as 2D nature with a sharp straight line along the kz direction. However, the kz dependence of bulk VB Γ_8^+ seemed to be weak and no TDS 3D features were detected along Γ-Z direction. It implied that there might be no phase transition from 3D-TI to TDS.

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