Quantum Spin Liquids in Correlated f-Electron Compounds

相关 f 电子化合物中的量子自旋液体

• 批准号: 1807451
• 负责人: Joseph Ross, Jr.
• 金额: $ 56.05万
• 依托单位: Texas A&M University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-08-15 至 2023-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1807451&HistoricalAwards=false
• 关键词: Quantum; Spin; Liquids; Correlated; Electron; Quantum; Spin; Liquids; Correlated; Electron

Nontechnical Abstract: Almost all materials will ultimately settle into an ordered state at the lowest temperatures. The situation would be much different in a universe that is one- or two dimensional, and where the exotic quantum spin liquid state may emerge. Understanding the ways in which the transport of heat and charge occurs in such a state is just beginning, and controlling it to create practical devices and sensors has emerged as a central challenge. This project will identify and synthesize new materials in search for a metallic quantum spin liquid. Neutron scattering experiments will be carried out at national facilities at Oak Ridge National Laboratory and at the National Institute of Standards and Technology. Both undergraduate and graduate students participate in all aspects of these experiments, receiving thorough training and broad experience in measurement techniques and applications that will prepare them to become effective future users of these national facilities. Technical Abstract: Quantum Spin Liquids (QSL) occur when magnetic order is overwhelmed by strong quantum fluctuations, giving rise to massively entangled ground states with unusual excitations, often with topological character. While metallic QSLs are expected to have a much richer range of phase behaviors, the few QSL systems discovered so far are all insulating. The discovery of intrinsically metallic QSLs where frustrated moments are coupled to itinerant conduction electrons has the potential to realize and to test theoretical predictions of exotic states and phases like unconventional superconductivity, ferromagnetism, and Dirac metals where excitations have photon-like dispersions. This project seeks to find the first examples of metallic QSLs among the f-electron based heavy fermions, and to explicate how the breakdown of conventional magnetic order or alternatively the formation of magnetic moments via the collapse of the Fermi surface can be generic routes to QSL formation in metals. The experimental program is based on the metallic R2T2X (R=Ce,Yb) compounds, where strong quantum fluctuations arise from competition between dimerization and magnetic order in both planar and chainlike morphologies. The high quality single crystals required to support this experimental program will be grown in our lab from metallic fluxes. Neutron diffraction, magnetometry, heat capacity, and electrical transport measurements will be primary tools for explicating the underlying magnetic and electronic phase diagrams, supplemented by inelastic neutron scattering measurements that will assess the corresponding development of magnetic fluctuations and correlations.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

非技术摘要：几乎所有材料最终都将在最低温度下定位为有序状态。在一个或二维的宇宙中，这种情况会大不相同，而外来量子旋转液态可能会出现。了解在这种状态下进行热量和电荷的运输方式，并且控制它以创建实用设备和传感器的控制已成为一个核心挑战。 该项目将识别并合成新材料，以寻找金属量子自旋液体。中子散射实验将在橡树岭国家实验室和国家标准技术研究所的国家设施进行。本科生和研究生都参与了这些实验的各个方面，在测量技术和应用方面都获得了彻底的培训和广泛的经验，这将使他们成为这些国家设施的有效未来用户的准备。 技术摘要：量子自旋液体（QSL）发生时，当磁性质量被强大的量子波动淹没，从而产生具有异常激发的大规模纠缠的基态，通常具有拓扑特征。尽管预期金属QSL的相位行为范围更丰富，但到目前为止发现的几个QSL系统都是绝缘的。发现本质上金属的QSL，使沮丧的矩与巡回传导电子耦合具有实现和测试异国情调状态和阶段的理论预测的潜力，以及诸如非常规的超导性，铁磁性，以及dirac金属以及激发具有光子样分散的情况。该项目旨在在基于F-电子的重型费米子中找到金属QSL的第一个例子，并阐明如何通过费米表面崩溃而形成磁矩的形成是如何成为金属中QSL形成的通用路线。实验程序基于金属R2T2X（R = CE，YB）化合物，其中强量量子波动是由平面和类似链状形态的二聚化和磁顺序之间的竞争引起的。支持该实验程序所需的高质量单晶将在我们的实验室中从金属通量中种植。中子衍射，磁力学，热量和电运输测量将是解释基础磁性和电子相图的主要工具，并补充了无弹性中子中子散射测量测量值，该测量将评估磁性波动的相应发展和相关性。这种奖项反映了NSF的法定任务和依据的依据，并通过评估了Intellial and Intellial and Intellial and Internial and Internial and Internial and the Internitial。