Physics of Non-Fermi-Liquid Metals

非费米液态金属物理学

• 批准号: 0706625
• 负责人: Qimiao Si
• 金额: $ 37万
• 依托单位: William Marsh Rice 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: 2007-09-15 至 2010-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0706625&HistoricalAwards=false
• 关键词: Physics; Non; Fermi; Liquid; Metals

TECHNICAL SUMMARY:This award supports theoretical research and education in condensed matter physics. The PI will focus on two complementary and intertwined subjects: the origins of non-Fermi liquid behavior and quantum criticality. On the one hand, experiments in strongly correlated materials have provided ample evidence for the failure of the conventional theory of electrons in solids, Landau's Fermi liquid theory. Understanding the mechanisms for non-Fermi liquid behavior is one of the fundamental issues with many open questions. On the other hand, a number of metallic systems have emerged as prototype materials in which quantum criticality can be systematically studied. The challenge to theory is enormous, because the critical fluctuations are both collective and quantum mechanical. Perhaps the most pressing question is whether the traditional picture based on order-parameter fluctuations is adequate, or whether inherently quantum degrees of freedom must be incorporated as part of the critical modes. These issues are important for a wide range of novel quantum materials, including heavy fermion metals, high temperature superconductors, and quantum nanostructures. The proposed research is comprised of three specific directions:1. Global phase diagram of magnetic heavy fermions: Here the PI will pursue the notion that quantum phases in magnetic heavy fermion metals are not only characterized by conventional order parameters, but also by the nature of their Fermi surface. Both antiferromagnetic and ferromagnetic heavy fermion systems will be considered, and the implications for quantum criticality will be addressed.2. Quantum phases in itinerant frustrated quantum magnets: The PI seeks to understand the origin of the singular heavy fermion behavior in f-electron metals with geometric frustration.3. Nonequilibrium aspects of Quantum Criticality: The PI will study the nonlinear transport and other non-equilibrium properties of a single-electron transistor with ferromagnetic leads, which can be tuned through a quantum critical point. This project not only is of interest in the context of nanostructures, but also provides a theoretically controlled setting to explore the non-equilibriums aspects of quantum criticality.This research project will engage junior scientists as well as undergraduate students, providing them with advanced theoretical training. The research will advance the understanding of electronic materials that are potentially important for thermoelectric, magnetic information, and spintronic technologies.NON-TECHNICAL SUMMARY:This award supports theoretical research and education in condensed matter physics. The discovery of complex metallic materials with unusual properties that lie outside the standard textbook description of metals has motivated intense research that aims to understand the physical origins of their properties. The PI will use advanced theoretical methods to attack this problem with a focus on elucidating the nature of a transformation from one state of matter to another that takes place at the absolute zero of temperature. In contrast to the familiar transformation of water to ice that takes place around 273K, or 0C, and in which temperature plays an important role, this transformation is driven by a fundamental principle of quantum mechanics ascribed to Heisenberg. The PI is developing a theory of these transformations and the unusual temperature dependent properties that they induce. This research project will engage junior scientists as well as undergraduate students, providing them with advanced theoretical training. The research will advance the understanding of electronic materials contributing to the intellectual foundations of possible new technologies, information and electronic device technologies in particular.

该奖项支持凝聚态物理学的理论研究和教育。PI将专注于两个互补和相互交织的主题：非费米液体行为和量子临界性的起源。一方面，强关联材料的实验为传统的固体电子理论--朗道的费米液体理论--的失败提供了充分的证据。理解非费米液体行为的机制是一个基本问题，有许多悬而未决的问题。另一方面，一些金属系统已经成为原型材料，可以系统地研究量子临界性。对理论的挑战是巨大的，因为临界涨落既是集体的，又是量子力学的。也许最紧迫的问题是，基于序参量涨落的传统图景是否足够，或者内在的量子自由度是否必须作为临界模式的一部分被纳入。这些问题对于各种新型量子材料都很重要，包括重费米子金属、高温超导体和量子纳米结构。本研究主要包括三个方向：1.磁性重费米子的全局相图：在这里，PI将追求磁性重费米子金属中的量子相不仅由常规序参数表征，而且还由其费米表面的性质表征。反铁磁和铁磁重费米子系统都将被考虑，量子临界性的影响将被解决。流动受抑量子磁体中的量子相：PI试图理解具有几何受抑的f电子金属中奇异重费米子行为的起源。量子临界性的非平衡方面：PI将研究具有铁磁引线的单电子晶体管的非线性传输和其他非平衡特性，这些特性可以通过量子临界点进行调谐。本研究项目不仅关注纳米结构，而且提供了一个理论控制的环境来探索量子临界性的非平衡方面。本研究项目将吸引初级科学家和本科生，为他们提供先进的理论培训。该研究将促进对热电、磁信息和自旋电子技术具有潜在重要性的电子材料的理解。非技术摘要：该奖项支持凝聚态物理学的理论研究和教育。复杂金属材料的发现具有不寻常的性质，超出了金属的标准教科书描述，激发了旨在了解其性质的物理起源的深入研究。PI将使用先进的理论方法来解决这个问题，重点是阐明在绝对零度下发生的从一种物质状态到另一种物质状态的转变的性质。与人们熟悉的在273 K或0 C左右发生的水到冰的转变不同，温度在其中起着重要作用，这种转变是由海森堡的量子力学基本原理驱动的。PI正在开发这些转变的理论，以及它们引起的不寻常的温度依赖性。该研究项目将吸引初级科学家和本科生，为他们提供先进的理论培训。该研究将促进对电子材料的理解，为可能的新技术，特别是信息和电子设备技术的知识基础做出贡献。