Noise and Aging in Disordered Magnetic Materials

无序磁性材料中的噪声和老化

• 批准号: 0605726
• 负责人: Michael Weissman
• 金额: $ 41.39万
• 依托单位: University of Illinois at Urbana-Champaign
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-07-01 至 2010-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0605726&HistoricalAwards=false
• 关键词: Noise; Aging; Disordered; Magnetic; Materials

*****NON-TECHNICAL ABSTRACT*****Technological advancement relies on the development of new materials with properties tailored to applications. For example, the devices that read the magnetic disks in computers rely on special types of material whose electrical resistance is very sensitive to magnetic fields. Although there are well-developed techniques for analyzing materials which have simple crystalline order, the broader class of materials which are not so well ordered, or which even look random ('glassy') are harder to analyze. This project focuses on the use of a technique, the study of random fluctuations ('noise'), to look at disordered magnetic systems, especially ones whose electrical resistance depends on magnetism. This technique allows one to obtain a much better picture of what components of a disordered system are responsible for its response to applied fields, and that in turn is useful for improving material design. One of the key purposes of this project is to train a postdoctoral fellow to become an expert in a collection of noise techniques developed over the years in this laboratory. Undergraduate researchers will also have an opportunity to perform small-scale, accessible science.*****TECHNICAL ABSTRACT*****A variety of qualitative characterizations of common disordered magnetic systems remain unsettled. The best known is the question of what sorts of states realistic spinglasses settle into. There are also many important systems (e.g. cobaltites) in which spinglass physics appears to coexist with domains of more conventional order. This project focuses on the use of noise to investigate disordered magnetic systems. Non-Gaussian noise in small samples of these systems provides a probe of the detailed internal states. It should allow discrimination, for example, between nearly independent ferromagnetic domains imbedded in a spinglass matrix and interacting ferromagnetic domains forming a larger-scale cluster glass. Small-scale fluctuation experiments on spinglasses provide fingerprints of individual states, which should help settle the question of how many non-symmetry-related states are available to several types of conducting spinglasses. Several remaining problems in manganites, particularly whether there are regimes best viewed as a strain-glass, are also amenable to these small-scale noise investigations. Aging investigations, also very sensitive to the form of glassy correlations, will be used in conjunction with the noise work. One of the key purposes of this project is to train a postdoctoral fellow to become an expert in a collection of noise techniques developed over the years in this laboratory. Undergraduate researchers will also have an opportunity to perform small-scale, accessible science

* 非技术摘要 * 技术进步依赖于开发具有适合应用的性能的新材料。例如，在计算机中读取磁盘的设备依赖于特殊类型的材料，其电阻对磁场非常敏感。虽然有发达的技术来分析具有简单晶体顺序的材料，但更广泛的材料类别不是那么有序，甚至看起来随机（“玻璃状”）更难分析。这个项目的重点是使用一种技术，研究随机波动（“噪声”），看看无序的磁性系统，特别是那些电阻取决于磁性。这种技术使人们能够更好地了解无序系统的哪些组成部分负责其对外加场的响应，这反过来又有助于改进材料设计。该项目的主要目的之一是培养一名博士后研究员，使其成为该实验室多年来开发的一系列噪声技术的专家。本科研究人员也将有机会进行小规模的，可访问的科学。技术摘要 * 普通无序磁系统的各种定性表征仍然没有解决。最著名的问题是，现实中的蜘蛛网会进入什么样的状态。还有许多重要的系统（例如钴矿），其中玻璃物理学似乎与更传统秩序的域共存。这个项目的重点是利用噪声来研究无序磁系统。这些系统的小样本中的非高斯噪声提供了详细的内部状态的探针。它应该允许歧视，例如，几乎独立的铁磁畴嵌入在spingglass矩阵和相互作用的铁磁畴形成一个较大规模的集群玻璃之间。spinglasses上的小尺度波动实验提供了单个状态的指纹，这应该有助于解决几种类型的导电spinglasses有多少非对称相关状态的问题。锰氧化物中的几个遗留问题，特别是是否存在最佳视为应变玻璃的制度，也适用于这些小规模的噪声调查。老化调查，也非常敏感的玻璃相关性的形式，将与噪音工作。该项目的主要目的之一是培养一名博士后研究员，使其成为该实验室多年来开发的一系列噪声技术的专家。本科研究人员也将有机会进行小规模的，可访问的科学