Non Fermi Liquid Physics and Quantum Critical Phenomena

非费米液体物理和量子临界现象

• 批准号: 0705847
• 负责人: Andrew Millis
• 金额: $ 39万
• 依托单位: Columbia University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-11-01 至 2010-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0705847&HistoricalAwards=false
• 关键词: Non; Fermi; Liquid; Physics; Quantum

TECHNICAL SUMMARY:This award supports theoretical and computational research and education in condensed matter physics. The research is aimed at developing and validating the concepts and the theoretical and computational methods needed to understand the physics of materials that do not obey the Landau Fermi liquid paradigm. There are 4 major components to the project: (1) The PI plans to carry out analytical and numerical calculations of model systems properties aimed at interpreting and understanding the implications of a new kind of experimental measurement; namely the "infrared/optical Hall effect," which probes the motion of electrons exposed to a static magnetic field and to an electric field alternating at infrared or optical frequencies. (2) This component focuses on "quantum criticality", the behavior occurring when the ground state of a material changes from one phase, for example paramagnetic metal, to another phase, for example antiferromagnetic metal. Materials near a quantum critical point typically exhibit large amplitude, long range, slowly changing fluctuations, which are known empirically to couple to the electrons, leading to large deviations from the predictions of fermi liquid theory. Moreover, the slow spatial and temporal variation of these fluctuations means that their effects can be studied using established techniques of quantum field theory. Analytical calculations will be performed, and compared to recent measurements on quasi two dimensional quantum antiferromagnetic transitions, with applications to high temperature superconductivity. (3) This component involves developing and validating new numerical methods for calculating the thermodynamics and dynamics of systems not adequately described by conventional methods. Considerable progress has been made in recent years based on the "dynamical mean field" approximation. New methods of solving the dynamical mean field equations have been developed and will be further improved, will be implemented for a wide range of systems, and applied. (4) The PI aims to extend our understanding of equilibrium physics into the nonequilibrium domain relevant for example for the nanoscience of molecular devices. New analytical and numerical methods will be explored for calculating the properties of systems in a steady state non-equilbrium situation.This research project will contribute to the training of young scientists who can look at problems from a broad perspective; combining fundamental insights with concrete applications.NON-TECHNICAL SUMMARY:This award supports theoretical and computational research and education in condensed matter physics. Why is the whole greater than the sum of its parts? How do simple constituents, the electrons and atoms which are the building blocks of the world around us, combine together to give amazing variety of things we see? This research project involves theoretical work designed to address these questions in one specific area of materials theory, namely the physics of "non-fermi-liquid" metals. "Fermi liquid theory", created by the Soviet physicist L. D. Landau in the late 1950s, is the reigning and widely successful intellectual paradigm for understanding the properties of electrons in metals. However, it fails conspicuously to describe for example the ability of the copper-oxide high temperature superconductor materials to carry a super-current with no electrical resistance at unprecedentedly high temperatures, the 'colossal' dependence of electrical resistance on magnetic field in manganese oxide compounds, or the changes to the conductance properties of nanoscale and "single molecule" devices. The experimental discovery of additional examples seems just around the corner. This research will contribute to the creation of new concepts and new theories, and new computational algorithms that will enable the understanding of complex materials with unusual properties that are the fuel for the discovery of new phenome and for the creation of new technologies. This research project will contribute to the training of young scientists who can look at problems from a broad perspective, combining fundamental insights with concrete applications, to tackle the future challenges of science and technology.

该奖项支持凝聚态物理学的理论和计算研究和教育。该研究旨在开发和验证概念以及理解不遵守朗道费米液体范式的材料物理所需的理论和计算方法。该项目有4个主要组成部分：（1）PI计划对模型系统属性进行分析和数值计算，旨在解释和理解一种新的实验测量的含义;即“红外/光学霍尔效应”，它探测暴露于静态磁场和以红外或光学频率交替的电场中的电子的运动。(2)该部分侧重于“量子临界性”，即当材料的基态从一个相（例如顺磁金属）变为另一个相（例如反铁磁金属）时发生的行为。量子临界点附近的材料通常表现出大幅度，长范围，缓慢变化的波动，这是已知的经验耦合到电子，导致费米液体理论的预测大偏差。此外，这些涨落在空间和时间上的缓慢变化意味着它们的影响可以用量子场论的现有技术来研究。分析计算将被执行，并比较最近的测量准二维量子反铁磁跃迁，与高温超导的应用。(3)该部分涉及开发和验证新的数值方法，用于计算传统方法无法充分描述的系统的热力学和动力学。近年来，在“动力学平均场”近似的基础上取得了相当大的进展。求解动力学平均场方程的新方法已经开发出来，并将得到进一步改进，将在广泛的系统中实施和应用。(4)PI旨在将我们对平衡物理学的理解扩展到非平衡领域，例如分子器件的纳米科学。该研究项目旨在培养能够从广阔的视角看待问题的年轻科学家，将基本的见解与具体的应用相结合。非技术性概要：该奖项支持凝聚态物理学的理论和计算研究以及教育。为什么整体大于部分之和？构成我们周围世界的简单成分，电子和原子，是如何联合收割机结合在一起，产生我们所看到的各种各样的东西？该研究项目涉及的理论工作旨在解决材料理论的一个特定领域，即“非费米液体”金属的物理学中的这些问题。“费米液体理论”，由苏联物理学家L。D.朗道在20世纪50年代后期，是统治和广泛成功的知识范式理解电子在金属中的性质。然而，它明显未能描述例如氧化铜高温超导体材料在前所未有的高温下携带超导电流而没有电阻的能力，氧化锰化合物中电阻对磁场的“巨大”依赖性，或者纳米级和“单分子”器件的电导特性的变化。实验发现更多的例子似乎指日可待。这项研究将有助于创造新概念和新理论，以及新的计算算法，从而能够理解具有不寻常特性的复杂材料，这些材料是发现新现象和创造新技术的燃料。该研究项目将有助于培养能够从广阔的角度看待问题的年轻科学家，将基本见解与具体应用相结合，以应对科学和技术的未来挑战。