Studies of Mesoscopic Spin Systems: Magnetic Molecules and Formalism

介观自旋系统的研究：磁性分子和形式主义

• 批准号: 0202165
• 负责人: Anupam Garg
• 金额: $ 21万
• 依托单位: Northwestern University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-07-01 至 2007-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0202165&HistoricalAwards=false
• 关键词: Studies; Mesoscopic; Spin; Systems; Magnetic

This award supports theoretical research and education in the study of magnetic macroscopic quantum phenomena and large magnetic molecules. The PI will investigate: (a) the magnetic properties of solids containing large magnetic molecules, (b) the semiclassical formalism for spin, and (c) unresolved physical issues in magnetic macroscopic quantum phenomena.The observations of hysteresis loop steps in the compounds commonly abbreviatedMn 12 and Fe 8 and oscillatory tunnel splittings in Fe 8, have opened new areas for the study of spin dynamics with novel interplays of quantal and classical behavior. The PI will study these single molecule magnets, especially the way in which they interact with their solid state environment. As an example, the PI will study how the sound propagation in these materials is affected by the magnetization dynamics, as a way of probing the latter. These studies are expected to elucidate magnetic hysteresis at the molecular level and to lead to ways of manipulating the dynamics of such systems. The formalism of the semiclassical limit for spin will be studied with a view to remedying gaps in present understanding. The physical origin of a rich and unexpected structure of degeneracies that has been discovered in models for Fe 8 and rotating nuclei will be sought. These degeneracies suggest an as yet undiscovered 'higher symmetry.' The PI will also exploit connections between molecular magnets and macroscopic quantum phenomena in magnets to examine outstanding questions that may impact future attempts to look for magnetic macroscopic quantum phenomena. This research also provides an environment for training of doctoral students at the frontiers of theoretical condensed matter physics.%%%This award supports theoretical research and education in the study of magnetic macroscopic quantum phenomena and large magnetic molecules. The work focuses on large molecules that have a large spin associated with them. The spin is large enough that it can be considered to be macroscopic, but at the same time small enough to exhibit various quantum mechanical phenomena, such as quantum mechanical tunneling of the spin orientation. Two examples of families of these large molecules are Mn12 and Fe8, in a standard shorthand notation. The PI will investigate: (a) the magnetic properties of solids containing large magnetic molecules, (b) the semiclassical formalism for spin, and (c) unresolved physical issues in magnetic macroscopic quantum phenomena. This work contributes to the intellectual foundation of quantum mechanical and magnetic phenomena in real materials and may contribute to future information and communication technologies. This research also provides an environment for training of doctoral students at the frontiers of theoretical condensed matter physics.***

该奖项支持磁性宏观量子现象和大磁性分子研究的理论研究和教育。PI将调查：（a）含有大磁性分子的固体的磁性，（B）自旋的半经典形式，（c）磁宏观量子现象中尚未解决的物理问题.对常见化合物Mn12和Fe8中磁滞回线台阶和Fe8中振荡隧道劈裂的观察，为自旋动力学的研究开辟了新的领域，具有量子和经典行为的新颖相互作用。PI将研究这些单分子磁体，特别是它们与固态环境相互作用的方式。作为一个例子，PI将研究这些材料中的声音传播如何受到磁化动力学的影响，作为探测后者的一种方式。这些研究有望在分子水平上阐明磁滞现象，并找到操纵此类系统动力学的方法。为了弥补目前认识上的空白，我们将研究自旋的半经典极限的形式。在Fe 8和旋转核的模型中发现了丰富的和意想不到的简并结构的物理起源将被寻求。这些简并性暗示了一种尚未发现的“更高对称性”。PI还将利用分子磁体和磁体中宏观量子现象之间的联系，研究可能影响未来寻找磁宏观量子现象的悬而未决的问题。这项研究还为培养理论凝聚态物理前沿的博士生提供了环境。%该奖项支持磁性宏观量子现象和大磁性分子研究的理论研究和教育。这项工作的重点是大分子，有一个大的自旋与他们有关。自旋足够大，可以被认为是宏观的，但同时又足够小，可以表现出各种量子力学现象，例如自旋取向的量子力学隧穿。这些大分子家族的两个例子是Mn12和Fe 8，采用标准速记符号。PI将调查：（a）含有大磁性分子的固体的磁性，（B）自旋的半经典形式，（c）磁宏观量子现象中未解决的物理问题。这项工作有助于真实的材料中量子力学和磁现象的知识基础，并可能有助于未来的信息和通信技术。这项研究还为理论凝聚态物理学前沿的博士生培训提供了环境。