微波辅助斯托纳粒子磁矩动力学研究
发布时间：2019-02-17 15:54
【摘要】：现代科学技术的不断发展和完善对硬盘磁盘等磁性信息存储器件的存储性能要求越来越高,研究设计更快速度和更高密度的磁性存储器件是研究者们一直致力研究的议题。由于磁性存储器件在生活中应用广泛,因此如何提高磁性材料的存储性能就显得非常重要,其中磁性材料的磁矩翻转问题是一个非常重要的研究课题,即如何提高磁性材料磁矩翻转效率以及降低其翻转过程中的翻转场等问题。磁性存储器件的存储密度和速度难以满足日新月异的科技发展对材料存储性能的要求,因此我们需要不断发展磁性存储技术以及信息快速存储与读取技术。磁性材料的磁矩翻转过程是极其复杂的,为了方便研究,本篇论文使用简化的单轴斯托纳粒子模型来研究磁矩翻转过程的动力学性质,这样不但可以大幅度节省时间还可以给实际应用带来一定的指导作用。本论文主要对变频椭圆微波场下斯托纳粒子磁矩翻转的动力学性质以及微波场辅助倾斜极化自旋极化电流磁矩翻转的动力学性质进行研究。文章的基本结构如下:第一章是引言,主要对本研究领域的背景和发展情况做简单介绍,并通过对领域内重要文献的梳理解读进一步理解本领域的研究进展。第二章是理论基础部分,主要介绍了研究磁矩翻转的基本方程即朗道-栗弗席兹-吉尔伯特(LLG)方程及其推导过程,并介绍了考虑自旋力矩项后的Landau-Lifshitz-Gilbert-Slonczewski(LLGS)方程。第三章研究的是椭圆偏振微波场辅助斯托纳粒子磁化矢量翻转的动力学性质,基于朗道-栗弗席兹-吉尔伯特方程研究磁矩翻转过程,考虑磁性单轴各向异性,通过分析及模拟研究磁矩翻转所需的临界翻转场和变化的微波频率幅度之间的关系。研究表明当椭圆偏振波两个方向的频率均接近铁磁共振频率时,会出现最小临界翻转场。第四章研究的是椭圆偏振微波场辅助倾斜极化自旋极化电流磁矩翻转的动力学性质。考虑粒子的磁性单轴各向异性,文章基于Landau-Lifshitz-Gilbert-Slonczewski(LLGS)方程,通过分析和模拟研究不同构型磁性自旋阀磁矩翻转过程中所需的阈值电流密度和微波场的幅度频率之间的关系。研究表明倾斜构型的磁性自旋阀可以有效地降低自由层磁矩翻转过程中所需的阈值电流密度。第五章是总结和展望章节,主要对研究工作进行总结并针对其中存在的有待解决的问题做出分析和展望。
[Abstract]:The continuous development and improvement of modern science and technology on the hard disk? The storage performance of magnetic information storage devices such as magnetic disks is becoming more and more demanding. The research and design of magnetic memory devices with faster speed and higher density has been the research topic of researchers. Because magnetic memory devices are widely used in daily life, how to improve the storage performance of magnetic materials is very important. Among them, the magnetic moment reversal of magnetic materials is a very important research topic. That is, how to improve the efficiency of magnetic moment reversal and reduce the turnover field. The storage density and speed of magnetic memory devices can not meet the requirement of material storage performance due to the rapid development of science and technology, so we need to develop magnetic storage technology and information fast storage and reading technology. The magnetic moment reversal process of magnetic materials is extremely complex. In order to facilitate the study, a simplified single-axis Stogner particle model is used to study the dynamic properties of the magnetic moment inversion process. In this way, it can not only save time greatly, but also bring some guidance to practical application. In this paper, the dynamic properties of the magnetic moment reversal of the Stoner particle under the frequency conversion elliptical microwave field and the dynamic properties of the magnetic moment reversal of the inclined polarization spin polarization current assisted by the microwave field are studied. The basic structure of the paper is as follows: the first chapter is the introduction, mainly introduces the background and development of this research field, and further understand the research progress through the combing and reading of the important literature in the field. The second chapter is the theoretical basis, mainly introduces the fundamental equation of magnetic moment reversal, i.e. Lando-Lifschitz Gilbert (LLG) equation and its derivation process. The Landau-Lifshitz-Gilbert-Slonczewski (LLGS) equation considering the spin moment term is also introduced. In chapter 3, the dynamical properties of magnetization vector flipping assisted by elliptical polarization microwave field are studied. The magnetic moment inversion process is studied based on Lando-Lifschitz Gilbert equation, and the magnetic uniaxial anisotropy is considered. The critical flipping field and the changing microwave frequency of magnetic moment flipping are studied by means of analysis and simulation. The relationship between ranges. It is shown that when the frequency of elliptical polarization wave in both directions is close to the frequency of ferromagnetic resonance, the minimum critical inversion field will occur. In chapter 4, the dynamical properties of the magnetic moment reversal of the inclined spin polarization current assisted by the elliptical polarization microwave field are studied. Considering the magnetic uniaxial anisotropy of particles, based on Landau-Lifshitz-Gilbert-Slonczewski (LLGS) equation, the threshold current density and the amplitude of microwave field during magnetic moment reversal of magnetic spin valves with different configurations are analyzed and simulated. The relationship between frequencies. It is shown that the inclined magnetic spin valve can effectively reduce the threshold current density required in the free layer magnetic moment reversal process. The fifth chapter is the summary and prospect chapter, mainly summarizes the research work and makes the analysis and prospect in view of the problems to be solved.
【学位授予单位】：苏州大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：O482.54;TP333
本文编号：2425333
[Abstract]:The continuous development and improvement of modern science and technology on the hard disk? The storage performance of magnetic information storage devices such as magnetic disks is becoming more and more demanding. The research and design of magnetic memory devices with faster speed and higher density has been the research topic of researchers. Because magnetic memory devices are widely used in daily life, how to improve the storage performance of magnetic materials is very important. Among them, the magnetic moment reversal of magnetic materials is a very important research topic. That is, how to improve the efficiency of magnetic moment reversal and reduce the turnover field. The storage density and speed of magnetic memory devices can not meet the requirement of material storage performance due to the rapid development of science and technology, so we need to develop magnetic storage technology and information fast storage and reading technology. The magnetic moment reversal process of magnetic materials is extremely complex. In order to facilitate the study, a simplified single-axis Stogner particle model is used to study the dynamic properties of the magnetic moment inversion process. In this way, it can not only save time greatly, but also bring some guidance to practical application. In this paper, the dynamic properties of the magnetic moment reversal of the Stoner particle under the frequency conversion elliptical microwave field and the dynamic properties of the magnetic moment reversal of the inclined polarization spin polarization current assisted by the microwave field are studied. The basic structure of the paper is as follows: the first chapter is the introduction, mainly introduces the background and development of this research field, and further understand the research progress through the combing and reading of the important literature in the field. The second chapter is the theoretical basis, mainly introduces the fundamental equation of magnetic moment reversal, i.e. Lando-Lifschitz Gilbert (LLG) equation and its derivation process. The Landau-Lifshitz-Gilbert-Slonczewski (LLGS) equation considering the spin moment term is also introduced. In chapter 3, the dynamical properties of magnetization vector flipping assisted by elliptical polarization microwave field are studied. The magnetic moment inversion process is studied based on Lando-Lifschitz Gilbert equation, and the magnetic uniaxial anisotropy is considered. The critical flipping field and the changing microwave frequency of magnetic moment flipping are studied by means of analysis and simulation. The relationship between ranges. It is shown that when the frequency of elliptical polarization wave in both directions is close to the frequency of ferromagnetic resonance, the minimum critical inversion field will occur. In chapter 4, the dynamical properties of the magnetic moment reversal of the inclined spin polarization current assisted by the elliptical polarization microwave field are studied. Considering the magnetic uniaxial anisotropy of particles, based on Landau-Lifshitz-Gilbert-Slonczewski (LLGS) equation, the threshold current density and the amplitude of microwave field during magnetic moment reversal of magnetic spin valves with different configurations are analyzed and simulated. The relationship between frequencies. It is shown that the inclined magnetic spin valve can effectively reduce the threshold current density required in the free layer magnetic moment reversal process. The fifth chapter is the summary and prospect chapter, mainly summarizes the research work and makes the analysis and prospect in view of the problems to be solved.
【学位授予单位】：苏州大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：O482.54;TP333
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