Emergent Properties of Highly Correlated Electronic Systems

高度相关电子系统的涌现特性

• 批准号: 0758356
• 负责人: Steven Kivelson
• 金额: $ 42万
• 依托单位: Stanford University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-10-01 至 2012-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0758356&HistoricalAwards=false
• 关键词: Emergent; Properties; Highly; Correlated; Electronic

TECHNICAL SUMMARY:This award supports research and education on emergent properties of highly correlated electronic systems. The main thrust of the research undertaken here is the effort at theoretical characterization of qualitatively new behaviors of interacting electrons (i.e. new states of matter) as well as new regimes of parameters in which familiar states of matter behave in new and different ways. In addition, some of the research explores qualitatively the relation between the microscopic interactions between electrons and the effective parameters that control the macroscopic behavior of solids.The search for new states of matter continues an ongoing effort by the PI in the theory of ''electronic liquid crystals.'' This work is based on an analogy between classical liquid crystals and corresponding phases of strongly interacting electrons. Electronic liquid crystals are quantum states with behaviors intermediate between a Fermi liquid and a Wigner crystal. Examples of such states have recently been observed experimentally: the anisotropic states (quantum Hall nematics) that are seen in high mobility quantum Hall devices and the metamagnetic nematic phase that has recently been identified in Sr3Ru2O7. The more microscopic issues to be addressed involve the physics of the superconducting Tc. A number of questions are addressed theoretically. What is it about superconductivity that causes transition temperatures, generally, to be so low, while other orders, such as ferromagnetism, frequently onset at much higher temperatures? Why is there, in the cuprate high temperature superconductors, an ''optimal'' doping at which Tc is maximal ? what is there an excess of in ''overdoped'' cuprates? Are there optimal mesoscale structures for superconductivity, structures that enhance the strength of the electron pairing without too strongly suppressing the superfluid stiffness? The research also seeks to interpret the importance of evidence of wide-spread mesoscale inhomogeneities in the cuprates ? both self-organized (i.e. stripes) and nucleated by disorder. The research is motivated by a need to clarify whether these observations are complicating details or essential to the mechanism of high temperature superconductivity.The effort undertaken has broader impacts with both scientific and educational consequences. Scientifically, there is impact in extending the understanding of the origins of high temperature superconductivity because that opens new theoretical opportunities as well as providing better ability to design materials with this highly desirable property. Involving students and postdoctoral researchers in the diverse problems and theoretical techniques used provides an exceptional training for talented young people. Past students and postdoctoral researchers have gone on to university faculty positions and their own careers in teaching and research and some have found successful positions in high tech companies and a variety of other fields outside of mainstream physics.NONTECHNICAL SUMMARY:This award supports research and education on exotic properties and unexplained electronic states of unusual materials. The broad thrust of the research undertaken here is the theoretical characterization of qualitatively new behaviors and new states of matter as well as investigating how familiar forms matter can be made to behave in new and different ways. This research explores these unusual states of matter by looking at the behavior of electrons and the microscopic level of the atoms that make up the material and then connecting those behaviors with the large scale properties which are seen in the material as a solid whole.The search for new states of matter continues an ongoing effort by the PI in the theory of ''electronic liquid crystals.'' This work develops theories of why some materials have electrons that are not just quiescently distributed more or less uniformly but which instead group together in various patterns.The issues to be addressed also involve the physics of the superconducting materials, those which can conduct electricity with no resistance and thus no waste of energy. The questions are quite basic. What is it about superconductivity that causes working temperatures, generally, to be so low? Why is there, in some high temperature superconductors, an ''optimal'' composition at which the working temperature is highest? Are there optimal ways of creating structures for superconductivity, structures that enhance performance? The research is motivated by a need to clarify which experimental observations are complicating details and which are essential clue to discovering to the mechanism needed to explain high temperature superconductivity.The effort undertaken has broader impacts with both scientific and educational consequences. Scientifically, there is impact in extending the understanding of the origins of high temperature superconductivity because that opens new theoretical opportunities as well as providing better ability to design materials with this highly desirable property. Involving students and postdoctoral researchers in the diverse problems and theoretical techniques used provides an exceptional training for talented young people. Past students and postdoctoral researchers have gone on to university faculty positions and their own careers in teaching and research and some have found successful positions in high tech companies and a variety of other fields outside of mainstream physics.

技术概述：该奖项支持对高度相关电子系统的紧急特性的研究和教育。这里进行的研究的主旨是努力从理论上描述相互作用电子(即新的物质状态)的新行为，以及熟悉的物质状态以新的和不同的方式表现的新的参数制度。此外，一些研究还定性地探索了电子之间的微观相互作用与控制固体宏观行为的有效参数之间的关系。寻找新的物质状态的努力继续着PI在“电子液晶”理论中的持续努力。这项工作是基于经典液晶和相应的强相互作用电子相之间的类比。电子液晶是介于费米液体和维格纳晶体之间的量子态。最近通过实验观察到了这种状态的例子：在高迁移率量子霍尔器件中看到的各向异性状态(量子霍尔向列相)，以及最近在Sr3Ru2O7中发现的亚磁向列相。需要解决的更微观的问题涉及超导超导的物理。从理论上解决了一些问题。超导性是什么导致转变温度通常如此低，而其他顺序，如铁磁性，经常在更高的温度下开始？为什么在铜酸盐高温超导体中，有一种“最佳”掺杂，在该掺杂温度下，T_c最大？在“过度掺杂”的铜酸盐中有什么过量？有没有最适合超导的介观结构，既能增强电子配对的强度，又不会太强烈地抑制超流体的刚性？这项研究还试图解释铜矿中广泛分布的中尺度不均匀证据的重要性？既有自组织的(即条纹)，也有无序成核的。这项研究的动机是需要澄清这些观测是复杂的细节，还是高温超导机制的关键。所做的努力具有更广泛的影响，既有科学上的影响，也有教育上的影响。从科学上讲，扩大对高温超导起源的理解是有影响的，因为这打开了新的理论机会，并提供了更好的能力来设计具有这种高度理想特性的材料。让学生和博士后研究人员参与到各种问题和理论技术中来，为有才华的年轻人提供了一种特殊的培训。过去的学生和博士后研究人员继续担任大学教师职位，并从事自己的教学和研究工作，有些人在高科技公司和主流物理以外的各种其他领域找到了成功的职位。非技术摘要：该奖项支持关于奇异性质和不寻常材料的不明电子状态的研究和教育。这里进行的研究的主要目的是从理论上描述物质的新行为和新状态，以及研究如何使熟悉的形式的物质以新的和不同的方式表现出来。这项研究探索了这些不寻常的物质状态，方法是观察电子的行为和组成材料的原子的微观水平，然后将这些行为与材料中被视为固体整体的大尺度性质联系起来。寻找新的物质状态的工作继续着PI在“电子液晶”理论中的持续努力。这项工作发展了为什么一些材料的电子不仅静止地或多或少均匀地分布，而是以各种模式聚集在一起的理论。需要解决的问题还涉及超导材料的物理，这种材料可以没有电阻地导电，因此不会浪费能量。这些问题是非常基本的。超导性是什么导致工作温度通常如此之低？为什么在某些高温超导体中，有一种工作温度最高的“最佳”成分？有没有为超导创造结构的最佳方法，这种结构可以提高性能？这项研究的动机是需要澄清哪些实验观察使细节复杂化，哪些是发现解释高温超导所需机制的基本线索。所做的努力具有更广泛的影响，既有科学上的影响，也有教育上的影响。从科学上讲，扩大对高温超导起源的理解是有影响的，因为这打开了新的理论机会，并提供了更好的能力来设计具有这种高度理想特性的材料。让学生和博士后研究人员参与到各种问题和理论技术中来，为有才华的年轻人提供了一种特殊的培训。过去的学生和博士后研究人员继续在大学担任教职，并在教学和研究方面从事自己的职业，一些人在高科技公司和主流物理以外的其他各种领域找到了成功的职位。