Complex Behavior Near the Metal-Insulator Transition

金属-绝缘体转变附近的复杂行为

• 批准号: 0542026
• 负责人: Vladimir Dobrosavljevic
• 金额: $ 33万
• 依托单位: Florida State University
• 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: 2006-03-01 至 2010-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0542026&HistoricalAwards=false
• 关键词: Complex; Behavior; Near; Metal; Insulator

Intellectual MeritThe metal-insulator transition (MIT) is one of the oldest, yet one of the fundamentally least understood problems in condensed matter physics. In the last few years, striking examples of complex ordering around the metal-insulator transition are starting to emerge, due to advances of both the experimental probes and the theoretical tools available. In many cases, fascinating new evidence reveals that genuinely new phenomena arise in presence of disorder and impurities. Put quite simply, a given configuration of impurities may locally favor one or another of several competing phases of matter. In many instances this gives rise to strongly inhomogeneous states that feature an enormous number of low-lying metastable configurations - producing qualitatively new excitations, slow relaxation, and glassy fluctuations and response. Even more surprisingly, recent work suggests that a plethora of intermediate heterogenous phases may emerge between the metal and the insulator, possibly even in absence of disorder. Such complexity emerges as a new paradigm of the metal-insulator transition region. These phenomena seem to dominate the observable properties in many physical systems, ranging from CMR manganites and high Tc cuprates, to two dimensional electron gases in MOSFETs, diluted magnetic semiconductors, and even the Kondo alloys.The topics that we plan to address in the next three years include: (1) Local quantumcriticality at the Mott-Anderson transition; (2) Role of long ranged RKKY interaction andrandom singlet correlations within the electronic Griffiths phase in the MIT critical region;(3) How is the metal-insulator transition modified in systems featuring strongly inhomogeneous (cluster) magnetic or charge-ordered phases? (4) Self-organized electron glasses and the MIT in doped Mott insulators.Broader ImpactFunding of the proposed work will allow the PI to integrate research at the forefront of condensed matter science in a world-class facility, and education at all academic levels: K-12, undergraduate, and graduate, through the following activities: (A) Outreach programs:The PI will continue to promote and enhance scientific and technological understanding andimportance of our research to the general public through various outreach activities. These will include: (1) Presenting lectures at elementary schools in order to popularize science and technology, and bring the most recent discoveries within reach of the youngest. (2) The PI will act as a Judge at annual Regional Science Fairs, as he has been doing over the last five years. These Fairs involve K-12 students from public and private school within the region; (3) The PI will participate in the FSU Physics Department Open House (PDOP) activities. (4) The PI will participate in the NHMFL Annual Open House activities. (B) Research Experiences for Undergraduates (REU) program. A REU Site has been established at the NHMFL. It hosts a summer internship program for undergraduates who come from all over the US. The PI will provide an opportunity for interns to spend two summer months working on one of the research projects. (C) FSU graduate students will be trained. The PI will supervise the research of several graduate students in physics, who will be supported from the NSF grant. In order for these activities to be effective, the PI needs to obtain funding that will allow him to conduct research at the forefront of condensed matter science.***

金属-绝缘体转变（MIT）是凝聚态物理学中最古老的问题之一，也是最不为人所知的问题之一。在过去的几年里，由于实验探针和理论工具的进步，围绕金属-绝缘体转变的复杂有序的引人注目的例子开始出现。在许多情况下，令人着迷的新证据表明，真正的新现象是在无序和杂质的存在下产生的。简单地说，给定的杂质结构可能局部地有利于物质的几个竞争相中的一个或另一个。在许多情况下，这会产生强烈的非均匀状态，其特征是大量的低位亚稳构型-产生质的新激发，缓慢弛豫，玻璃状波动和响应。更令人惊讶的是，最近的研究表明，在金属和绝缘体之间可能会出现过多的中间异质相，甚至可能在没有无序的情况下。这种复杂性作为金属-绝缘体过渡区的新范例出现。从CMR锰氧化物和高温铜氧化物，到MOSFET中的二维电子气，稀磁半导体，甚至Kondo合金，这些现象似乎支配着许多物理系统中可观测到的性质。（2）长程RKKY相互作用和随机单重关联在MIT临界区电子Griffiths相中的作用;（3）在具有强非均匀（团簇）磁性或电荷有序相的系统中，金属-绝缘体相变是如何改变的？(4)更广泛的影响拟议工作的资金将允许PI在世界一流的设施中整合凝聚态科学前沿的研究，以及所有学术水平的教育：K-12，本科生和研究生，通过以下活动：（A）推广计划：研究所会继续透过不同的外展活动，向公众披索和加强对科学和技术的认识，以及研究的重要性。这些措施包括：（1）在小学举办讲座，以普及科学和技术，并使最新的发现在最年轻的人能够接触到。(2)PI将在年度区域科学博览会上担任评委，就像他在过去五年中所做的那样。这些博览会涉及该地区公立和私立学校的K-12学生;（3）PI将参加FSU物理系开放日（PDOP）活动。(4)PI将参加NHMFL年度开放日活动。(B)本科生研究经验（REU）计划。在NHMFL建立了一个REU站点。它为来自美国各地的本科生举办暑期实习计划。PI将为实习生提供一个机会，让他们在夏季的两个月里从事其中一个研究项目。(C)FSU研究生将接受培训。PI将监督几个物理学研究生的研究，他们将得到NSF的资助。为了使这些活动有效，PI需要获得资金，使他能够在凝聚态科学的前沿进行研究。