Frustration and Order in Heavy Fermions on the Shastry-Sutherland Lattice

沙斯特里-萨瑟兰晶格上重费米子的挫败与有序

• 批准号: 1310008
• 负责人: Meigan Aronson
• 金额: $ 56万
• 依托单位: SUNY at Stony Brook
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-05-15 至 2016-10-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1310008&HistoricalAwards=false
• 关键词: Frustration; Order; Heavy; Fermions; Shastry

****Technical Abstract****This award aims to explicate the process by which electrons that are initially localized on the f-orbitals of rare earth based heavy fermion compounds can be induced to join the itinerant states comprising the Fermi surface(FS), and the critical fluctuations of the electronic structure that accompany this electronic de-confinement transition. The role of frustration in suppressing magnetic order in heavy fermions that form on the geometrically frustrated Shastry-Sutherland lattice will be investigated. Two distinct ground states are envisaged: a spin liquid where the conduction electrons are decoupled from the fluctuating moments, whose electrons are consequently excluded from the FS, and a Fermi liquid, where a strong Kondo effect delocalizes the f-electrons, which are now incorporated in an expanded FS. These two non-ordered states are separated at T=0 by a purely electronic transition, driven by fluctuations between the large and small FS states. The synthesis of new materials to support both the measurement program of the PI and those of her collaborators is a central theme of this project. Participating undergraduate and graduate students will gain practical and portable experience in a variety of different synthesis and experimental techniques. This research makes extensive use of national research facilities, including neutron scattering centers at NIST and Oak Ridge National Laboratory. ****Non-Technical Abstract****While all materials are disordered at high temperatures, with no discernible patterns or correlations in their configurations, the onset of an ordered phase such as superconductivity or magnetism is overwhelmingly favored as the temperature is reduced. This project seeks to explicate the properties of systems with the most extreme form of order, which occurs exactly at a temperature of absolute zero. The quantum mechanical nature of such a phase transition is paramount, with the result that normal behaviors like the conduction of heat or electricity are drastically modified- even at nonzero temperatures. Here, geometrical constraints associate with a lattice of magnetic moments will be used to realize such T=0 transitions, and their properties will be studied using neutron scattering experiments carried out at NIST and at Oak Ridge National Laboratory. The synthesis of new materials to support both the measurement program of the PI and those of her collaborators is a central theme of this project. Participating undergraduate and graduate students will gain practical and portable experience in a variety of different synthesis and experimental techniques.

****技术摘要****该奖项旨在解释最初定位在稀土基重费米子化合物f轨道上的电子可以被诱导加入包含费米表面（FS）的流动状态的过程，以及伴随这种电子去约束跃迁的电子结构的临界波动。挫折感在抑制重费米子磁序中的作用将被研究，这些重费米子形成于几何受挫的Shastry-Sutherland晶格上。设想了两种不同的基态：一种是自旋液体，其中传导电子与波动矩解耦，其电子因此被排除在FS之外；另一种是费米液体，其中强烈的近田效应使f电子离域，现在被纳入扩展的FS。这两个无序态在T=0时被一个纯电子跃迁分离，这是由大小FS态之间的波动驱动的。合成新材料来支持PI和她的合作者的测量程序是这个项目的中心主题。参与的本科生和研究生将获得各种不同合成和实验技术的实用和便携经验。这项研究广泛使用了国家研究设施，包括NIST的中子散射中心和橡树岭国家实验室。****非技术摘要****虽然所有材料在高温下都是无序的，在它们的结构中没有可识别的模式或相关性，但随着温度的降低，有序相（如超导或磁性）的开始是压倒性的有利的。这个项目试图解释系统的性质与最极端形式的秩序，这恰好发生在绝对零度的温度。这种相变的量子力学性质是至关重要的，其结果是，即使在非零度温度下，热传导或导电等正常行为也会被彻底改变。在这里，与磁矩晶格相关的几何约束将被用来实现这种T=0跃迁，它们的性质将通过在NIST和橡树岭国家实验室进行的中子散射实验来研究。合成新材料来支持PI和她的合作者的测量程序是这个项目的中心主题。参与的本科生和研究生将获得各种不同合成和实验技术的实用和便携经验。