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Title: | 拓樸絕緣體自旋閥之電子傳輸 Electronic Transport of Topological Insulator Spin Valves |
Authors: | Tai-Wen Zhong 鐘台文 |
Advisor: | 薛文証 |
Keyword: | 拓樸絕緣體,克萊恩傳輸,轉移矩陣,電導,自旋閥,磁阻, topological insulator,Kleining tunneling,transfer matrix,conductance,spin valve,magnetoresistance, |
Publication Year : | 2017 |
Degree: | 碩士 |
Abstract: | 本論文建構拓樸絕緣體表面上層狀結構的電子傳播行為模型,推導出電子在有限層數結構內的穿透率、電流、電導以及磁阻率等公式,接著探討拓樸絕緣體表面上不同的位障以及改變位障強度、寬度、結構週期數及排列方式對電子傳輸的影響,明顯看到施予電壓位障並不會使克萊恩穿隧通道消失,且穿透率能帶和電子入射角始終對稱,而鐵磁性材料所引起的磁位障則會打破拓樸絕緣體的時間-反轉對稱性,正向入射通道關閉,禁帶的出現使得某些能量下的電子無法穿透。
最後研究拓樸絕緣體自旋閥中的磁阻效應,發現雙層位障及週期性位障結構之磁阻率因共振效應而比單層位障結構更大,最高可達-7300%。 In this thesis, the propagation behavior model of electron of layered structure on the topological insulator surface is constructed. The transmission, current, conductance and magnetoresistance of the finite layered structure are calculated. Then, the influence of different potential barrier on the topological insulator surface and the barrier strength, width, the period of structural and the arrangement for the electron transport are investigated. It is obvious that the application of the voltage barrier does not cause the Klein tunneling to disappear. Besides, the transmission spectra and the angle of incidence are always symmetrical. Magnetic barrier arising from ferromagnetic material will break the time reversal symmetry of topological insulator and cause normally incident channel to close. In addition, a forbidden band to make electron unable to transmit completely in some energy region is presented. Finally, the magnetoresistance effect in the spin valve of the topological insulator is studied. It is found that the magnetoresistance of the double-layer barrier and the periodic barrier structure is larger than the single-layer barrier structure due to resonance effect, and up to -7300%. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/77761 |
DOI: | 10.6342/NTU201702165 |
Fulltext Rights: | 未授權 |
Appears in Collections: | 工程科學及海洋工程學系 |
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ntu-106-R04525106-1.pdf Restricted Access | 3.46 MB | Adobe PDF |
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