Theory of magnetic and nonmagnetic excitations in low-dimensional and nanostuctured materials

低维和纳米结构材料中的磁性和非磁性激发理论

• 批准号: 36357-2007
• 负责人: Cottam, Michael
• 金额: $ 2.05万
• 依托单位: University of Western Ontario
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2011
• 资助国家: 加拿大
• 起止时间: 2011-01-01 至 2012-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=474655
• 关键词: Theory; magnetic; nonmagnetic; excitations; low

The primary objective of this research is a theoretical study of the wave-like disturbances, known as collective excitations, that can occur in low-dimensional solid structures where typically the length scale in one or more of the dimensions may be as small as a few (or a few tens of) nanometres. The disturbances can, for example, be fluctuations in the magnetization (as in a spin wave or magnon), in atomic vibrations (as in phonons), or in electromagnetic fields (as in polaritons). The types of structures of interest include thin films, multilayers (such as superlattices which have a regular repeat pattern or periodicity), nanowires, nanotubes and nanodots (either singly or formed in arrays). All of these are capable of being fabricated to remarkable precision by modern growth techniques. A common feature is that the waves or excitations are extensively modified due to the very small length scale and the boundary regions (the surfaces and interfaces) in such structures, and therefore may show properties quite different from those in bulk materials. A fundamental understanding of these effects is important, both for the basic physics and for identifying their potential for applications (e.g, as high-frequency nanostructure devices and information storage devices). I am interested in novel aspects concerned with the nonlinear dynamical properties of these structures and materials, i.e., in cases where the waves interact with one another. This is in addition to the need for extending previous work in the linear (or noninteracting) regime to different materials and geometries (e.g. arrays of nanotubes and nanodots, or patterned surfaces). The theoretical methods include the use of advanced analytical techniques (such as many-body theory and quantum field theory) and, in some cases, numerical simulations (such as quantum and classical Monte-Carlo methods). Detailed applications will be made to inelastic light scattering and other experimental techniques for investigating the excitations in these systems. A major emphasis in this project will be to linear and nonlinear spin waves in ordered magnetic materials, where interesting effects can occur because of spatial localization and competing types of interactions.

这项研究的主要目的是对波浪样干扰（称为集体激发）的理论研究，可以在低维固体结构中发生，在低维固体结构中，通常在一个或多个维度中的长度尺度可能会像几个（或几个）纳米一样小。例如，在磁化强度（如旋转波或镁中），原子振动（如在声子中）或电磁场（如Polaritons中的磁子）中，这些干扰可能是波动的。 感兴趣的结构的类型包括薄膜，多层层（例如具有规则重复模式或周期性的超级晶格），纳米线，纳米管和纳米模子（单独或在阵列中形成）。 所有这些都能够被现代增长技术捏造为显着的精确度。 一个共同的特征是，由于长度尺度非常小，边界区域（表面和界面）在此类结构中进行了广泛的修改，因此可能显示出与散装材料中的属性完全不同。 对这些影响的基本理解对于基本物理学和确定其应用的潜力（例如，作为高频纳米结构设备和信息存储设备）都是重要的。 我对与这些结构和材料的非线性动力学特性有关的新颖方面感兴趣，即在波浪相互作用的情况下。 这是为了将线性（或非相互作用）制度中以前的工作扩展到不同的材料和几何形状（例如纳米管和纳米模子的阵列或图案表面）。 理论方法包括使用先进的分析技术（例如多体理论和量子场理论），在某些情况下是数值模拟（例如量子和经典蒙特卡洛方法）。 将对非弹性光散射和其他实验技术进行详细应用，以研究这些系统中的激发。 该项目的主要重点将是在有序的磁性材料中线性和非线性自旋波，在这种材料中，由于空间定位和相互作用的竞争类型，可能会出现有趣的效果。