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標題: | 自旋波在磁性多層膜中的電子特性 Electronic Properties of Spin Waves in Magnetic Multilayers |
作者: | Wei-Tang Chang 張威棠 |
指導教授: | 薛文証 |
關鍵字: | 自旋波,磁性多層膜,荷斯坦-普里梅科夫轉換,交換能,轉移矩陣,剛性交換常數,色散關係, spin wave,magnetic multilayers,Holstein-Primakoff transformation,exchange energy,transfer matrix,stiffness exchange constant,dispersion relation, |
出版年 : | 2012 |
學位: | 碩士 |
摘要: | 本論文主旨為研究自旋波在磁性多層膜中的電子特性。首先我們介紹磁性物質的種類以及內部能量,接著我們以自旋波的波向量大小將自旋波分為三個區域─交換區域、交換-靜磁區域、靜磁區域來個別探討,對於靜磁區域我們使用靜磁模式下的馬克斯爾方程式和華爾克方程式,讓我們能夠分別對於外加磁場平行以及垂直結構表面兩種情況做定性上的分析並且得到色散關係;在交換區域我們利用荷斯坦-普里梅科夫轉換和哈密頓來求得原子平面層與層之間的轉移矩陣,並且針對週期性多層膜結構做出數值分析並探討;在交換-靜磁區域需要同時考慮到交換作用和偶極-偶極作用的貢獻,我們使用朗道-利弗席茲方程式並且利用交換剛性常數和交換常數連繫了兩者間的關係,最後考慮同時滿足微觀和巨觀下的邊界條件,並且透過數值分析來找出自旋波頻率變化。 The main purpose of this thesis is to investigate the electronic properties of spin waves in magnetic multilayers. At first the magnetic properties and internal energies of the materials are introduced. Then according to the magnitude of the wave vector the spin wave problems are divided into three regions, exchange region, dipole-exchange region, magnetostatic region and analyzed respectively. In the magnetostatic region, the magnetostatic form of Maxwell equations and Walker’s equation are used to do analysis and derive the spin-wave dispersion relation of external magnetic field parallel or perpendicular to the material plane. In the exchange region, Holstein-Primakoff transformation and Hamiltonian are used to find transfer matrix of periodic superlattice and do analysis. In the dipole-exchange region, both contributions from exchange interaction and dipole-dipole interaction are considered. Therefore, both macroscopic and microscopic model are connected by exchange constant and stiffness exchange constant, and Landau-Lifshitz equation are used to solve the problem with appropriate boundaries. Finally figure out the change of frequency of spin waves through numerical analysis. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/16229 |
全文授權: | 未授權 |
顯示於系所單位: | 工程科學及海洋工程學系 |
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