Disorder and the emergence of inhomogeneous phases in strongly correlated electron systems

强相关电子系统中的无序和不均匀相的出现

• 批准号: 1005625
• 负责人: Peter Hirschfeld
• 金额: $ 27万
• 依托单位: University of Florida
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-10-01 至 2014-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1005625&HistoricalAwards=false
• 关键词: Disorder; emergence; inhomogeneous; phases; strongly

TECHNICAL SUMMARY This award supports theoretical and computational research and educational activities related to the problem of inhomogeneous competing order in metals. An increasing number of novel materials exhibit emergent inhomogeneous phases, which are states of matter where the ground state is modulated and may display various types of long-range order. The theory of such states, which represents a fundamental departure from the basic momentum-space one-particle paradigms of condensed matter physics, is still in its infancy. Along this direction, the PI will study the general question of how inhomogeneous order emerges and how the particular choice taken by the system depends on disorder, interactions, and its electronic structure. Models will be studied which are applicable to a diverse class of interacting systems, appropriate for heavy fermion, iron-pnictide, cuprate, and other oxide materials. An improved understanding of the role of disorder in the presence of competing ordered states will facilitate the identification of the most important instabilities in various systems, and enable researchers to focus on the intrinsic aspects of exotic ordering phenomena such as high temperature superconductivity. This award supports research, which is ultimately expected to have an impact on the design and development of oxide materials for applications. It is noteworthy that the entire electronics industry is built on doped semiconductor devices at present, and may be said to have been so successful in part because solutions were found to prevent electron mobilities from being limited by disorder which accompanies the doping process. Since in correlated systems and novel oxides in particular, impurities have a much more important impact, specifically through their nucleation of inhomogeneous phases, these problems represent important and also practical hurdles to be surmounted before oxide electronics can succeed in the marketplace. The PI will train two graduate students during the course of the project. The PI will also engage in outreach activities to educate school children in the Gainesville area about superconductivity and notions of order and disorder which are important in many disciplines of science. NONTECHNICAL SUMMARY This award supports theoretical and computational research and educational activities related to the problem of "inhomogeneous competing order" in metals. This fascinating situation occurs when a complex material is close to making a transition from one electronic phase to another, and two or more different quantum mechanical states become so close in energy as to be essentially indistinguishable. Rather than deciding to form in one or the other of these states, in the presence of small amounts of impurities or imperfections, the material sometimes forms an inhomogeneous state, which varies in composition from point to point in space. Materials that exhibit such exotic behavior can be potentially tuned for use in so-called smart materials which can improve the way many different electronic devices work. In this project, the PI will perform theoretical calculations and computer simulations on a variety of novel materials where disorder is known to play a role of this type, to understand how superconductivity, an electronic state that can conduct electricity without resistance, and magnetism can be influenced by impurities. This is fundamental research aimed to advance our understanding of materials that are very sensitive to impurities and imperfections leading to unusual quantum mechanical states of electrons. Many of these states appear to be connected to superconductivity. This research contributes to understanding key properties of materials that lead to superconductivity.The PI will train two graduate students during the course of the project. The P.I. will also engage in outreach activities to educate schoolchildren in the Gainesville area about superconductivity and notions of order and disorder which are important in many disciplines of science.

技术摘要 该奖项支持与金属不均匀竞争顺序问题相关的理论和计算研究以及教育活动。越来越多的新型材料表现出新出现的非均质相，这些相是基态被调制的物质状态，并且可能表现出各种类型的长程有序。这种状态的理论与凝聚态物理的基本动量空间单粒子范式存在根本背离，目前仍处于起步阶段。沿着这个方向，PI 将研究非均匀有序如何出现以及系统所采取的特定选择如何取决于无序、相互作用及其电子结构的一般问题。将研究适用于各种相互作用系统的模型，适用于重费米子、铁磷化物、铜酸盐和其他氧化物材料。更好地理解无序在竞争有序态存在下的作用将有助于识别各种系统中最重要的不稳定性，并使研究人员能够专注于高温超导等奇异有序现象的内在方面。该奖项支持研究，最终预计将对氧化物材料应用的设计和开发产生影响。值得注意的是，目前整个电子工业都是建立在掺杂半导体器件之上，可以说之所以如此成功，部分原因在于找到了防止电子迁移率受到掺杂过程中伴随的无序限制的解决方案。由于在相关系统和特别是新型氧化物中，杂质具有更重要的影响，特别是通过它们的非均匀相成核，这些问题代表了氧化物电子产品在市场上取得成功之前需要克服的重要且实际的障碍。 PI 将在项目期间培训两名研究生。 PI 还将开展外展活动，对盖恩斯维尔地区的学童进行超导性以及有序与无序概念的教育，这些概念在许多科学学科中都很重要。非技术摘要 该奖项支持与金属中“不均匀竞争秩序”问题相关的理论和计算研究以及教育活动。当复杂材料即将从一种电子相转变为另一种电子相，并且两个或多个不同的量子力学状态的能量变得如此接近以至于基本上无法区分时，就会发生这种令人着迷的情况。在存在少量杂质或缺陷的情况下，材料有时不会形成这些状态中的一种或另一种，而是形成一种不均匀的状态，其成分在空间中的点与点之间发生变化。表现出这种奇异行为的材料有可能被调整用于所谓的智能材料，从而改善许多不同电子设备的工作方式。在这个项目中，PI将对各种已知无序在其中发挥作用的新型材料进行理论计算和计算机模拟，以了解超导性（一种可以无电阻导电的电子态）和磁性如何受到杂质的影响。这是一项基础研究，旨在增进我们对对杂质和缺陷非常敏感的材料的理解，这些材料会导致不寻常的电子量子力学状态。其中许多状态似乎与超导性有关。这项研究有助于理解导致超导性的材料的关键特性。项目负责人将在项目过程中培训两名研究生。 P.I.还将开展外展活动，对盖恩斯维尔地区的学童进行超导性以及有序与无序概念的教育，这些概念在许多科学学科中都很重要。