本論文量測鎳奈米線因自發熱所造成的電阻變化，利用穩態焦耳熱及電阻檢溫理論得到其熱傳導係數，實驗分成兩個部分探討鐵磁性材料鎳奈米線在不同磁壁密度與固定在不同外加靜磁場對溫度變化的熱傳導係數。
實驗一：量測鎳奈米線在不同磁壁密度於溫度變化60-300K的熱傳導係數，結果顯示熱傳導係數在較高的磁壁密度狀態較小，室溫下鎳奈米線的熱傳導係數約為鎳塊材的31%，勞倫茲常數明顯小於理論值2.44×10-8 WΩ/K2，顯示鎳奈米線不適用威德曼-法蘭茲定律(Wiedemann-Franz law)。實驗二：量測鎳奈米線固定在不同靜磁場下於溫度變化10-300K的熱傳導係數，結果顯示靜磁場會抑制磁振子和部分聲子的熱傳輸行為，靜磁場愈大造成熱傳導係數愈小，直到靜磁場大於510 Gauss熱傳導係數減小幅度趨於緩和，室溫下鎳奈米線的熱傳導係數約為鎳塊材的30%，勞倫茲常數也明顯小於理論值2.44×10-8 WΩ/K2，顯示鎳奈米線亦不適用威德曼-法蘭茲定律。

This work measures the resistance difference of Ni nanowire from self-heating by using steady-state joule heating and electrical-resistance thermometry. Finally, we obtain the thermal conductivity of Ni nanowire. The experiments divide into two parts of Ni nanowires in different domain wall density and in different magnetic field to investigate the relationship between temperature and thermal conductivity. First, we measure the thermal conductivity in different domain wall density at temperature between 60 and 300K. Results show that thermal conductivity in higher domain wall density is smaller than in lower one. The thermal conductivity of Ni nanowires is about 31% of bulk at 300K and Lorentz number is obviously less than theoretical value 2.44×10-8 WΩ/K2. Second, we measure the thermal conductivity fixed in different static magnetic field at temperature between 10 and 300K. Results show that magnon and part of phonon are suppressed heat conduction by field. The thermal conductivity in higher field is smaller and until the field higher than 510 Gauss thermal conductivity tends to constant. The thermal conductivity of Ni nanowires is about 30% of bulk at 300K and Lorentz number is obviously less than theoretical value 2.44×10-8 WΩ/K2. Results show Ni nanowires are not followed Wiedemann-Franz law.
Keywords：Ni nanowires, thermal conductivity, domain wall, magnetic field, and Lorenz number

摘要 I
Abstract II
誌謝 III
目錄 IV
圖目錄 VI
表目錄 VIII
符號表 IX
第一章 緒論 1
1.1 前言 1
1.2 文獻回顧--奈米線的熱傳導性質 2
1.2.1 單根多壁碳奈米管的熱傳導性質 2
1.2.2 半導體微奈米線的熱傳導性質 3
1.2.3 鐵磁材料奈米線的熱傳導性質 7
1.3 研究動機與目的 13
1.4 研究方法 13
第二章 理論基礎與文獻回顧 14
2.1 熱傳導係數 14
2.1.1 電子的熱傳導 15
2.1.2 聲子的熱傳導 18
2.1.3 磁振子的熱傳導 23
2.2 熱傳導係數的測量方法 26
2.2.1 自發熱與電阻檢溫量測方法 27
2.2.2 平行熱傳導量測法 28
2.2.3 三倍頻量測法 29
2.3 磁性材料 31
2.3.1 磁區 31
2.3.2 磁壁 32
2.3.3 磁壁幾何異向性 33
2.4 原子力顯微鏡技術 35
第三章 樣品製作與研究方法 36
3.1 懸空鎳奈米線結構製作 36
3.1.1 樣品製作流程 36
3.1.2 金電極陣列基板 37
3.2 鎳奈米線結構的磁力分佈 38
3.3 實驗量測系統與架構 38
3.3.1 低溫量測系統 39
3.3.2 熱傳導係數在不同磁壁密度與溫度的關係 40
3.3.3 熱傳導係數在不同外加靜磁場與溫度的關係 41
第四章 實驗結果與討論 42
4.1 懸空鎳奈米線結構 42
4.2 鎳奈米線磁力分布圖 43
4.3 鎳奈米線在不同磁壁密度與溫度的關係 45
4.3.1 電阻率在不同磁壁密度與溫度的關係 45
4.3.2 熱傳導係數在不同磁壁密度與溫度的關係 46
4.3.3 勞倫茲常數在不同磁壁密度與溫度的關係 48
4.4 鎳奈米線在施加不同靜磁場與溫度的關係 50
4.4.1 電阻溫度係數 51
4.4.2 熱傳導係數固定在不同靜磁場與溫度的關係 51
4.4.3 勞倫茲常數與溫度的關係 53
第五章 結論 56
參考文獻 57

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