Magnetization Dynamics and Orbital Magnetism

磁化动力学和轨道磁学

• 批准号: 9820230
• 负责人: Andrew Zangwill
• 金额: $ 24万
• 依托单位: Georgia Tech Research Corporation
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-04-01 至 2003-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9820230&HistoricalAwards=false
• 关键词: Magnetization; Dynamics; Orbital; Magnetism

9820230ZangwillThis award supports education and research on magnetism and magnetic moments at surfaces. Magnetic moments near monoatomic step edges experience anisotropy to spin rotation that differs from that of moments in the bulk. This difference is a consequence of the spin-orbit interaction at step edges where low site symmetry leads to poor quenching of atomic orbital angular momentum. The proposed theoretical work focuses on two aspects of surface magnetism: macroscopic (classical) and microscopic (quantum). At the classical level, the PI proposes to study the magnetization dynamics of spatially inhomogeneous magnetic states that are impressed on an island morphology typical of as-grown epitaxial films. Conjugate gradient and spin relaxation numerical methods will be used to simulate an appropriate Heisenberg block spin model with magnetostatics, global four-fold anisotropy, and local two-fold anisotropy at island edges. One focus is on the mobility of a Neel magnetic domain wall as a function of the step anisotropy strength and the complexity of the growth morphology. A second problem is the formation of and dynamics of XY-type vortex states rendered locally stable by the step edge anisotropy. At the quantum level, the PI will study orbital-magnetism using current-density functional theory, which is needed to capture the vestiges of Hund's rules that must occur at step edges due to incomplete angular momentum quenching. Simple models will be studied at first, but a long-term goal is to develop a practical method for performing calculations on more sophisticated and realistic models. Another aim of this work is to seek a formal basis for the phenomenological Maxwell equations for matter. %%%This award is for research and education in the theory of magnetism at surfaces of materials. The PI's approach involves the study of surface phenomena involving magnetism on long length scales and the development of new computational methods to determine how magnetism arises from atoms in microscopic environments with lower symmetry than that for an atom in the bulk. Such environments occur at surfaces and these techniques may contribute to the development of future nanotechnologies.***

9820230 Zangwill该奖项支持表面磁性和磁矩的教育和研究。 单原子台阶边缘附近的磁矩经历各向异性自旋旋转，不同于在散装的时刻。 这种差异是在台阶边缘的自旋轨道相互作用的结果，其中低站点对称性导致原子轨道角动量的淬火差。 拟议的理论工作集中在两个方面的表面磁性：宏观（经典）和微观（量子）。在经典的水平上，PI建议研究的磁化动力学的空间不均匀的磁状态，印象深刻的典型的生长外延膜的岛屿形态。 共轭梯度和自旋弛豫数值方法将被用来模拟一个适当的海森堡块自旋模型与静磁，全球四重各向异性，并在岛边缘的局部两重各向异性。 一个重点是作为阶跃各向异性强度和生长形态的复杂性的函数的Neel磁畴壁的移动性。 第二个问题是由于阶跃边缘各向异性而局部稳定的XY型涡旋状态的形成和动力学。在量子水平上，PI将使用电流密度泛函理论研究轨道磁性，这是为了捕获由于不完全角动量淬灭而必须发生在台阶边缘的洪德规则的痕迹。 首先将研究简单的模型，但长期目标是开发一种实用的方法，用于对更复杂和现实的模型进行计算。 这项工作的另一个目的是寻求一个正式的基础上的现象学麦克斯韦方程组的物质。这个奖项是为了奖励在材料表面磁性理论方面的研究和教育。 PI的方法涉及研究涉及长尺度磁性的表面现象，以及开发新的计算方法来确定微观环境中原子的磁性如何产生，其对称性低于散装原子。 这种环境发生在表面，这些技术可能有助于未来纳米技术的发展。*