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****该奖项旨在阐明最初位于稀土基重费米子化合物f轨道上的电子被诱导加入构成费米面（FS）的巡回态的过程），以及伴随电子去限制转变的电子结构的临界波动。 我们将研究挫败在抑制几何挫败 Shastry-Sutherland 晶格上形成的重费米子磁序方面的作用。设想了两种不同的基态：一种自旋液体，其中传导电子与波动矩解耦，其电子因此被排除在FS之外；以及一种费米液体，其中强烈的近藤效应使f电子离域，这些电子现在被合并在扩展的 FS 中。这两个无序状态在 T=0 时通过纯电子跃迁分开，由大 FS 状态和小 FS 状态之间的波动驱动。合成新材料以支持 PI 及其合作者的测量计划是该项目的中心主题。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践和便携经验。这项研究广泛利用了国家研究设施，包括 NIST 和橡树岭国家实验室的中子散射中心。 ****非技术摘要****虽然所有材料在高温下都是无序的，其结构中没有明显的模式或相关性，但随着温度的降低，超导或磁性等有序相的出现是绝对有利的。该项目旨在解释具有最极端秩序形式的系统的属性，这种秩序恰好发生在绝对零温度下。 这种相变的量子力学性质至关重要，其结果是，即使在非零温度下，热传导或电传导等正常行为也会发生巨大改变。 在这里，与磁矩晶格相关的几何约束将用于实现这种 T=0 跃迁，并且将使用在 NIST 和橡树岭国家实验室进行的中子散射实验来研究它们的特性。合成新材料以支持 PI 及其合作者的测量计划是该项目的中心主题。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践和便携经验。