臺灣博碩士論文加值系統

透過鍍膜速率的調配(中能量電子繞射MEED監視薄膜成長)及歐傑電子能譜儀(AES)的成分分析之雙重校正 ? 磁性合金超薄膜CoxNi1-x/Cu(100)的合金比例及厚度能夠被精準的掌控。其中厚度準確率達0.05個原子層(平均值) ? 合金比的誤差則在 ± 0.5% 內。因此我們可以研究極小的Co成分變化 ? 對於晶格結構、表面形貌和磁性行為上的影響。在磁性方面 ? 磁易軸轉向的臨界厚度dc對Co的量非常敏感 ; 當合金比例分別為x = 0、3、5.5、8 %時 ? dc = 7~8、9~10、13~14、17~18個原子層。而當x = 10%時 ? 直到20.6原子層的厚度內 ? 合金薄膜的磁易軸則總是在膜平面上 ? 並沒有隨厚度而有轉向的行為發生。在另一方面 ? 透過低能量電子繞射的分析(LEED、I/V-LEED) ? 晶格結構及表面形貌並沒有隨膜厚及合金比而明顯變化。所以由以上的結果可以明顯的釐清 ? 這麼敏感的磁易軸轉向行為是由於當平均3d電子數隨合金比例被調動時 ? 造成磁異向性能量劇烈變化所導致的 ? 與晶格結構及表面形貌並無直接明顯的關係。

Magnetic alloy ultrathin films CoxNi1-x/Cu(100) were prepared to characterize its behavior of spin reorientation transition (SRT). With the double check of MEED oscillation and quantitative AES analysis, the composition of the alloy films was determined within an accuracy of ± 0.5 %, which allows us to prepare alloy films in very low Co concentration. So the sensitive effect of alloy composition in crystalline structure, morphology and magnetic properties can be characterized in situ by LEED, I/V-LEED and MOKE. The critical thickness of spin reorientation transition (SRT) in magnetic alloy ultrathin films CoxNi1-x /Cu(100) were 7~8, 9~10, 13~14, 17~18 ML for x = 0, 3, 5.5, 8 % respectively, and for x = 10 %, alloy films always reveal in-plane anisotropy up to 20.6 ML. Despite of the composition induced very different SRT behavior when x ￡ 10%, the vertical inter-layer distance and the morphology of all the films did not show any significant difference. Comparing with other experimental and theoretical results, it is concluded that the magnetic properties such as magnetic anisotropy were extremely sensitive to the average filling 3d electron in the alloy films.

摘要 3
ABSTRACT 4
CONTENT 5
1. INTRODUCTION 6
2. BASIC CONCEPTS 8
2.1 Film growth 8
2.2 Magnetic anisotropy 9
2.3 Magnetic hysteresis loop 14
3. EXPERIMENT APPARATUS AND THEORY 16
3.1 Ultra-high vacuum (UHV) system 18
3.2 Magneto-optical Kerr effect 19
3.2.1 Introduction 19
3.2.2 Apparatus 20
3.3 LEED & I/V-LEED 23
3.4 MEED 26
3.5 AES 28
3.5.1 Theory and apparatus 28
3.5.2 Preparation of homogeneous film coverage 34
3.6 Calibration of alloy composition and thickness 36
4. RESULTS 49
4.1 Growth mode (MEED) 49
4.2 Crystalline structure (I/V-LEED) 50
4.3 Crystalline structure and morphology (LEED) 53
4.4 Spin reorientation transition (SRT) 55
4.5 Canted magnetization 61
4.6 Thermodynamic effect 65
5. DISCUSSION 73
5.1 Co concentration induced significant delay on dc 73
5.2 Canted magnetization 73
5.3 Thermodynamic effect 74
6. SUMMARY 76
REFERENCES 77

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