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研究生:黃靖雅
研究生(外文):HUANG, JING-YA
論文名稱:碳鈷異質界面在電場下的磁化行為調控
論文名稱(外文):Voltage-induced Reversible Change Magnetization Behavior in Cobalt/Amorphous Carbon Interface
指導教授:許華書許華書引用關係
指導教授(外文):HSU, HUA-SHU
口試委員:許慈方廖彥發
口試委員(外文):HSU, TZU-FANGLIAO, YEN-FA
口試日期:2020-07-09
學位類別:碩士
校院名稱:國立屏東大學
系所名稱:應用物理系光電暨材料碩士班
學門:自然科學學門
學類:物理學類
論文種類:學術論文
論文出版年:2020
畢業學年度:108
語文別:中文
論文頁數:34
中文關鍵詞:碳異質結構磁圓二色性光譜儀石墨化電控磁特性
外文關鍵詞:Carbon heterostructureMagnetic Circular DichroismGraphitizationVoltage ControlMagnetism
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  透過施加電場來達到調控碳鈷異質界面之間的磁性現象是本實驗目的,因為近年來的磁學研究中,研究電控磁性界面的領域有了快速的發展,且已被證實能夠電控非磁性層與鐵磁層間磁矩的磁化特性、磁阻和磁異向性。而本實驗更是使用了能量解析的方式,來觀測碳鈷異質界面的自旋極化態密度(DOSs),其中碳更被認為是未來研究並運用在電子元件上的潛在材料。因此,此研究實現了「運用外加電場調控鐵磁性金屬鈷/非晶質碳異質界面的磁特性」,藉由磁圓二色性光譜儀(MCD)其使用能量來量測其自旋極化現象,更利用X光吸收光譜(XAS)來量測施加電場下的樣品,並了解到金屬鈷/非晶質碳異質結構中的電子結構與局域配位數的變化。MCD的數據中,在低能量區域量測到一個較寬的訊號,而高能量區域則量測到完整封閉的峰值,因此猜測較寬的MCD訊號為金屬鈷的d軌域所產生的磁光訊號,而高能量則與受金屬鈷/非晶質碳界面影響,所以轉角度並通電場的情況下,更能夠觀察到明顯的MCD-H可逆變化,其變化經由XAS的量測證實,證實樣品經外加電場的影響,其電荷累積在金屬鈷/非晶質碳間,導致費米能階發生改變,進而影響MCD-H的數值變化。而這樣的現象將會為自旋電子學中的碳基材料應用開啟新的篇章。
  Controlling the magnetic-related phenomena of a medium via applied voltage is a rapidly developing research field in modern magnetism. Voltage (V) control of magnetism, magnetoresistance, magnetic anisotropy, and magnetization in a ferromagnetic layer exchange-coupled to a nonmagnetic layer has recently been reported. However, to explore the origin of observed phenomena by directly studying spin polarized density of states (DOSs) of these heterostructures is rare and necessary. Carbon (C) has also been considered as a potential material for future electronics application. Therefore, in this work, ferromagnetic metal Co/C heterostructures were fabricated for realization V controlled magnetism evidenced by optical magnetic circular dichroism (MCD) measurements, which can measure the spin polarized DOSs directly. The in-situ x-ray absorption spectra (XAS) measurements with applied voltage has also been employed to clarify further the electronic structures and local structures of these elements in Co/C heterostructures. In such Co/C samples, a following sizeable MCD effect was observed. One broad MCD signal in low energy region was obtained, while the other shows a peak in the high energy region while applied a magnetic field. Interestingly, the MCD hysteresis loops reveal different behaviours. We propose that the broad MCD signal arises from the optical transitions between Co d orbitals or bands of metallic Co and the peak in high energy region could be related to Co/C interface. And the MCD hysteresis loops can be reversibly controlled by applied V. The XAS measurements give important information about the charge accumulation at the Co/C interface. The charge accumulation will lead to change of the Fermi level and the coupling of Co/C, therefore, changing the MCD hysteresis loops. These results would open new a perspective for C based spintronics application.
致謝 I
摘要 II
Abstract III
圖目錄 VI
表目錄 VIII
第一章 序論 1
1.1 前言 1
1.2 研究動機 2
1.3 文獻回顧 3
1.3.1 3
Voltage-induced reversible changes in the magnetic coercivity of Fe/ZnO heterostructures
1.3.2 4
Unraveling Dzyaloshinskii-Moriya Interaction and Chiral Nature of Graphene/Cobalt interface
1.3.3 5
Manipulation of the magneto-optical properties of a Co/C heterostructure under an applied voltage
1.3.4 6
Electrical manipulation of a topological antiferromagnetic state
第二章 儀器設備之原理 7
2.1 製備樣品之儀器 7
2.1.1射頻磁控濺鍍系統(RF Magnetron Sputter System) 7
2.2 實驗量測之儀器 8
2.2.1磁圓二色性光譜儀(Magnetic Circular Dichroism, MCD) 8
2.2.2阻抗頻譜(Electrical Impedance Spectroscopy, EIS) 9
2.2.3 X光吸收光譜儀(X-ray Absorption Spectroscopy, XAS) 11
2.2.4 拉曼光譜儀(Raman Spectroscopy) 12
2.2.5穿透式電子顯微鏡(Transmission Electron Microscopy, TEM) 13
第三章 實驗製備與設計 14
3.1 樣品製備 14
3.1.1濺鍍系統 14
3.1.2靶材與基板鍍膜前處理 14
3.1.3實驗步驟 15
3.2 量測設計 16
3.2.1磁圓二色性光譜儀下 16
3.2.2 X光吸收光譜儀下 17
3.2.3拉曼光譜儀下 17
第四章 實驗初步結果 18
4.1磁光量測分析 18
4.1.1入射光角度 19
4.1.2外加磁場 21
4.1.3外加電場 22
4.2 X光吸收光譜分析 24
4.3 阻抗頻譜分析 25
4.4拉曼光譜分析 28
4.5 TEM圖像化分析 29
第五章 數據整合與討論 30
參考文獻 34

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【2】Lin, W. C., Chang, P. C., Tsai, C. J., Shieh, T. C., & Lo, F. Y. (2014). Voltage-induced reversible changes in the magnetic coercivity of Fe/ZnO heterostructures. Applied Physics Letters, 104, 062411.
【3】Ajejas, F., Gudín, A., Guerrero, R., Anadón, A., Manuel, J., Melo, L., … & Perna, P. (2018). Unraveling Dzyaloshinskii-Moriya Interaction and Chiral Nature of Graphene/Cobalt interface. Nano Letters, 18, 9, 5364–5372.
【4】Hsu, H. S., Chang, Y. C., Huang, J. Y., Huang, Y. H., Liao, Y. F., Lee, J. S., … & Yao, Y. D. (2018). Manipulation of the magneto-optical properties of a Co/C heterostructure under an applied voltage. Carbon, 140, 10-16
【5】Tsai, H., Higo, T., Kondou, K., Nomoto, T., Sakai, A., Kobayashi, A., … & Nakatsuji, S. (2020). Electrical manipulation of a topological antiferromagnetic state. Nature, 580, 608–613.
【6】Kelly, P. J. & Arnell, R. D. (2000). Magnetron sputtering: a review of recent developments and applications. Vacuum, 56, 159-172.
【7】Mohanty, N. K., Satpathy, S. K., Behera Banarji, Nayak, P. & Choudhary, N. P. (2012). Complex impedance properties of LiSr_2 Nb_5 O_15 ceramic. Journal of Advanced Ceramics, 1, 221–226.
【8】Bumbrah, G. S. & Sharma, R. M. (2016). Raman spectroscopy – Basic principle, instrumentation and selected applications for the characterization of drugs of abuse. Egyptian Journal of Forensic Sciences, 6, 209-215.
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【10】Ferrari, A. C. & Robertson, J. (2000). Interpretation of Raman spectra of disordered and amorphous carbon. Physical Review B, 61, 14095.

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