實驗室所研究的鉛金合金有極大的Rashba effect，本論文主要研究合金表面覆蓋層對其能帶結構的影響。先前研究合金薄膜時覆蓋層為金原子，為了驗證覆蓋層的影響，我們將覆蓋層改為鉍原子，利用角解析光電子能譜(ARPES)與低能量電子繞射儀(LEED)觀察合金薄膜隨蒸鍍鉍的變化。本實驗主要利用熱蒸鍍方式成長合金薄膜，在室溫與低溫下蒸鍍鉍原子。由實驗結果顯示，室溫下蒸鍍鉍原子能帶給底下合金層Rashba effect，得到與用金當覆蓋層相似的能帶結構。藉由分析合金能帶強度的變化，顯示出合金能帶隨鉍蒸鍍量增加而增強，證實覆蓋層的重要性；另一方面，低溫下鍍鉍無法得到合金能帶結構，從LEED與理論計算模型的探討，我們推測可能是覆蓋層原子排列位置不對。
　　從上述實驗中，我們證實能藉由改變覆蓋層的原子來調控合金的Rashba effect，使其能帶結構改變，且覆蓋層原子需排列在特定位置才行，此結果顯示我們理論計算模型是正確的。另外從鉛單晶與鉛薄膜實驗的比較，我們推測Rashba參數α_R極可能隨覆蓋層原子改變，顯示調控Rashba effect的可行性。

The previous research shows that that a binary alloy composed of heavy atoms, Pb and Au, has large Rashba effect, yielding two cones at Γ ̅ and two giant Rashba splitting at M ̅. Experiments and first-principles calculations of the electronic structure indicated that such a Rashba effect may be produced only via a special buckling configuration induced by squeezing from the top Au capping layers and bottom Pb films. In this research, we demonstrated that with Bi as the capping layer on PbAu alloy, the Rashba effect is reproduced as well. This result means that Rashba-splitting band structure of PbAu alloy layer is caused by a capping layer on the top, which breaks the inversion symmetry and enhances the buckling height.
We tried to deposit Bi onto PbAu alloy layer at Room temperature and low temperature, T = -130 ˚C, respectively and found that Rashba-splitting band structure only showed up at room temperature. It means that the atoms of capping layer must be at specific locations that are commensurate with Au atoms of alloy. In addition, we found that the binding energy of Rashba-splitting band structure shifted into higher binding energy and dispersion changed, indicating that we can use different kinds of atoms as the capping layer to tune the Rashba effect of the middle alloy.

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