本篇論文研究 Sr2Y(Ru1-xCux)O6、FeSe 單晶與 xFeSe0.35Te0.65多晶 樣品的拉曼散射光譜響應，有下列重要的實驗結果：Sr2YRuO6的 421 cm-1、567 cm-1及 763 cm-1拉曼活性振動模的半高寬隨著銅離子摻雜 量的增加而變大，權重值減小，與銅離子的摻雜造成 Ru-O 八面體的 減少及其排列有序度變差有關，Y-O 與 Ru-O 八面體氧離子伸張振動 模的頻率位置隨著摻雜銅離子濃度增加分別展現大量紅移 (約 11 cm-1) 與少量藍移 (約 3 cm-1)，顯示銅離子的摻雜對於相鄰的 Y-O 八 面體影響較顯著，我們推測 Y-O 與 Ru-O 八面體的鍵長改變與 Cu-O 八面體的楊-泰勒效應有關。Sr2YRuO6的二階與一階拉曼峰的強度比 值隨著銅離子摻雜量的增加而變大，經由 Sr2Y(Ru1-xCux)O 的光學電 導率數據證實，銅離子摻雜量上升，使得樣品的能隙值縮減，由此造 成入射光子能量更為接近樣品吸收峰，共振拉曼效應的增強使得二階 散射訊號明顯。Sr2YRuO6單晶在弱鐵磁耦合特徵溫度 (TC = 135 K) 附近，315 cm-1、763 cm-1、1152 cm-1 及 1449 cm-1拉曼峰的頻率大量 藍移且半高寬變窄，為自旋-聲子交互作用增強所致。低溫下的二階 與一階拉曼峰強度比值上升，推測存在楊-泰勒能隙，且其自陷態激 子的生命期隨著溫度降低而增加。對於未摻雜銅離子的樣品，當溫度
160
161
論估算的結果，由於 Eg(2) 拉曼峰的強度微弱，導致 δ 比值誤差明顯。
另外，1350 cm-1與 1600 cm-1處顯現 2 個微弱的高頻拉曼散射訊號，
為 Fe-3d 軌域電子分別自 d
x
2-y
2 躍遷至 dxz
與 dyz
的貢獻，
當鐵的質量 數增加，兩個拉曼峰的頻率差值縮小，乃因四面體晶格擴張，使得晶 格場頂點的硒離子遠離中心的鐵離子，Fe-3d 軌域受到硒離子位能微 擾降低所致。在接近 100 K 與超導相變溫度 13 K 附近時，我們發現 三種鐵同位素樣品的拉曼峰羅侖茲模型擬合參數隨著溫度的改變具 有多個地方展現不一致性，可能與樣品的品質有關。未來我們希望藉由測量 Sr2Y(Ru1-xCux)O6 的紅外光反射光譜、角 度解析光電子能譜學，或使用掃描穿隧顯微技術 (scanning tunneling microscopy)，探究 Sr2Y(Ru1-xCux)O6 的超導能隙，冀能夠更深入了解 超導態的庫柏對與聲子之間的關聯性。並且希望能夠針對不同 Se 含 量的鐵同位素 Fe(Se,Te) 系列樣品進行低溫拉曼散射光譜量測，以釐 清晶格聲子在結構與超導相轉變溫度附近的異常變化有何關聯性。
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