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定位在稀土基的重型费米斯化合物F-轨道上的电子的过程，以加入包含费米表面（FS）（FS）的流动状态，以及该电子结构伴随这种电子结构的关键性波动，这些电子结构伴随着这种电子结构的电子结构。 挫败感在抑制磁性秩序中的作用将在沉重的费米子中形成，这些磁性在几何沮丧的sustry-sutherland晶格上的作用。设想了两个不同的接地状态：一种自旋液体，其中传导电子与波动矩的传导电子被解耦，因此，其电子被排除在FS中，而Fermi液体则将强大的亲to效应脱离Fermi液体，该效应将F-ELECTRON脱离了Fermi效应，而F-electrons现在已融合在扩展的FS中。这两个非定分状态通过纯电子过渡在t = 0的情况下分离，这是由大和小型FS状态之间波动驱动的。合成新材料以支持PI的测量计划和其合作者的测量计划是该项目的核心主题。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式经验。这项研究广泛使用了国家研究设施，包括NIST和Oak Ridge国家实验室的中子散射中心。 ****非技术抽象****虽然所有材料在高温下均无序，但在其配置中没有明显的模式或相关性，但随着温度降低，诸如超导性或磁性等有序阶段的发作（例如超导性或磁性）受到了压倒性的青睐。该项目旨在解释具有最极端形式的系统的属性，该系统完全发生在绝对零的温度下。 这种相变的量子机械性质至关重要，结果是，即使在非零温度下，诸如热量或电的传导或电的正常行为也会发生巨大修饰。 在这里，将使用与磁矩晶格相关的几何约束来实现此类T = 0过渡，并将使用在NIST和Oak Ridge国家实验室进行的中子散射实验来研究其性能。合成新材料以支持PI的测量计划和其合作者的测量计划是该项目的核心主题。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式经验。