https://scholars.lib.ntu.edu.tw/handle/123456789/71965
標題: | 磁性多層膜材料中自旋波傳遞 Spin Wave Transport in Magnetic Multilayer |
作者: | 吳誌維 Wu, Chih-Wei |
關鍵字: | 磁子;自旋波;交換作用;靜磁模式;Landau-Lifshitz方程式;色散關係;位能函數;能帶結構;magnon;spin wave;exchange effect;magnetostatic mode;Landau-Lifshitz equation;dispersion relation;potential function;band structure | 公開日期: | 2009 | 摘要: | 本論文主要的目的在於研究磁性多層膜結構中自旋波傳遞的情形。我們首先以自旋波向量的大小來將分析的問題區分成四個區域,在微觀的觀點下我們透過各自旋間的海森堡交互作用力來分析鐵磁性材料,並得到色散關係式;在交換區域內則是使用Landau-Lifshitz方程式來求解鐵磁材料內的動態磁化強度;在靜磁區域內則是透過靜磁形式的馬克斯威爾方程式來做分析並得到色散關係式。最後進一步分析具有表面的鐵磁性波導和具有界面的週期性結構,在鐵磁性波導中我們先推導出外加磁場方向與鐵磁性材料平面垂直和平行兩種情況下的位能函數,並透過數值分析發現當外加磁場方向與鐵磁性材料平面平行時,位能函數在邊界上出現微分不連續的情形;週期性結構方面則是推導鐵磁性材料/鐵磁性材料和鐵磁性材料/非磁性材料結構下的色散關係式,同樣透過數值分析找出能帶結構的變化。 This thesis is intended studying the spin wave transport in the magnetic multilayer. First we divided the analyzed problems into four regions since the magnitude of the wave vector. At the microscopic viewpoint, we through that spins with nearest-neighbor spins coupled by the Heisenberg interaction to analyze the ferromagnetic material and derive the dispersion relation. In the exchange region, we use the Landau-Lifshitz equation to solve the dynamic magnetization in the ferromagnetic material. In the magnetostatic region, we can use the magnetostatic form of Maxwell equations to do analysis and derive the dispersion relation. In the last, we further analysis the problems of ferromagnetic waveguide with surfaces and periodic structure with interfaces. In the ferromagnetic waveguide, we derived the potential function of the external magnetic field perpendicular to the ferromagnetic material plane and parallel to the ferromagnetic material plane. Through the numerical analysis to know that when the external magnetic field parallel to the ferromagnetic material plane then the potential function on the boundary will be differential discontinuous. In the periodic structure side, we derived the dispersion relation of the ferromagnetic/ferromagnetic structure and the ferromagnetic/non-magnetic structure. Also through the numerical analysis we can figure out the change of band structure. |
URI: | http://ntur.lib.ntu.edu.tw//handle/246246/188991 |
顯示於: | 工程科學及海洋工程學系 |
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ntu-98-R96525060-1.pdf | 23.53 kB | Adobe PDF | 檢視/開啟 |
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