Complex Behavior Near the Metal-Insulator Transition

知识价值金属-绝缘体转变(MIT)是凝聚态物理学中最古老、但从根本上最不被理解的问题之一。在过去的几年里，由于实验探针和可用的理论工具的进步，围绕金属-绝缘体转变的复杂有序化的显著例子开始出现。在许多情况下，引人入胜的新证据表明，真正的新现象出现在无序和杂质存在的情况下。简而言之，给定的杂质构型可能在局部有利于物质的几个相互竞争的阶段中的一个或另一个。在许多情况下，这会引起以大量低位亚稳态组态为特征的强烈不均匀状态--产生定性的新激发、慢弛豫和玻璃化的波动和响应。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式应运而生。这些现象似乎主导着许多物理系统的可观测性质，从CMR锰氧化物和高T_c铜酸盐，到MOSFET中的二维电子气，稀磁半导体，甚至是Kondo合金。我们计划在未来三年内讨论的主题包括：(1)Mott-Anderson相变的局域量子临界性；(2)MIT临界区电子Griffiths相内长程RKKY相互作用和随机单重态关联的作用；(3)如何在具有强烈不均匀(团簇)磁性或电荷有序相的系统中改变金属-绝缘体的转变？(4)自组织电子玻璃和掺杂Mott绝缘体中的MIT。拟议工作的建立将使PI能够通过以下活动整合凝聚态科学前沿的研究和所有学术水平的教育：K-12，本科生和研究生：(A)外联计划：PI将继续通过各种外联活动促进和加强对科学和技术的理解和我们的研究对公众的重要性。这些将包括：(1)在小学举办讲座，以普及科学技术，并将最新的发现带给最年轻的人。(2)一如过去五年的做法，私家侦探将担任每年一度的地区科学博览会的评委。这些展会有来自该地区公立和私立学校的K-12学生参加；(3)国际学生联合会将参加FSU物理系开放日(PDOP)活动。(4)该协会将参加NHMFL年度开放日活动。(B)本科生研究经验(REU)方案。在NHMFL已经建立了一个REU站点。它为来自美国各地的本科生举办暑期实习项目。PI将为实习生提供一个机会，让他们在夏季花两个月的时间从事其中一个研究项目。(C)对外国语大学的研究生进行培训。PI将监督几名物理学研究生的研究，他们将得到NSF拨款的支持。为了使这些活动有效，国际和平研究所需要获得资金，使他能够在凝聚态科学的前沿开展研究。

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.***