Complex Behavior Near the Metal-Insulator Transition

金属-绝缘体跃迁（MIT）是凝聚态物理中最古老的问题之一，但也是最不容易理解的问题之一。在过去的几年里，由于实验探针和理论工具的进步，金属-绝缘体转变周围复杂有序的惊人例子开始出现。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存在的情况下出现的。简单地说，一种给定的杂质结构可能局部地倾向于物质的几个相互竞争的相中的一个或另一个。在许多情况下，这产生了具有大量低洼亚稳态构型的强非均匀态——产生定性的新激发、慢弛豫和玻璃态波动和响应。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，甚至可能没有混乱。这种复杂性是金属-绝缘体过渡区的新范式。这些现象似乎主导了许多物理系统的可观察性质，从CMR锰矿石和高Tc铜酸盐，到mosfet中的二维电子气体，稀释磁性半导体，甚至是近藤合金。我们计划在未来三年内解决的主题包括：(1)莫特-安德森跃迁的局部量子临界性；(2)远程RKKY相互作用和随机单线态相关在MIT临界区电子Griffiths相位中的作用；(3)在具有强不均匀（团簇）磁相或电荷有序相的系统中，金属-绝缘体跃迁是如何改变的？(4)掺杂Mott绝缘体中的自组织电子玻璃与MIT。更广泛的影响拟议工作的资金将使PI能够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，本科和研究生，通过以下活动：(a)外展计划：PI将继续通过各种外展活动促进和加强科学和技术的理解以及我们的研究对公众的重要性。这些措施包括：(1)在小学举办讲座，普及科学技术，使最年轻的孩子能够接触到最新的发现。(2) PI将担任年度区域科学博览会的评委，就像他过去五年所做的那样。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。（二）本科生科研经历项目。已在国家边界线足球联盟设立了一个REU场址。它为来自美国各地的本科生举办了一个暑期实习项目。该项目将为实习生提供一个机会，让他们花两个月的时间从事其中一个研究项目。(C) FSU研究生将得到培训。PI将指导几名物理学研究生的研究，这些研究生将得到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

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.***