Correlated Matter under Extreme Conditions

极端条件下的相关物质

• 批准号: 0706553
• 负责人: Collin Broholm
• 金额: $ 36万
• 依托单位: Johns Hopkins 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: 2007-09-01 至 2011-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0706553&HistoricalAwards=false
• 关键词: Correlated; Matter; under; Extreme; Conditions

****NON-TECHNICAL ABSTRACT****Cooled to sufficiently low temperatures matter generally takes on a solid crystalline form. In rare cases however, fluctuations normally only found at higher temperatures can persist to the absolute zero temperature. Such materials present profound scientific challenges and they have unusual responses to external stimuli which are of interest for applications. This project seeks to understand and control strongly fluctuating matter by subjecting it to extreme conditions of pressure, stress, magnetic fields, and electric fields. Extreme conditions drive such materials between strongly fluctuating and conventional crystalline phases thus exposing mechanisms behind the anomalous properties. The materials will be probed by neutron scattering, a technique that provides detailed information about atomic scale structure and motion. The experiments will be carried out on materials that contain strings or planes of interacting magnetic ions that do not form crystalline magnetic states under ambient conditions. Some of the materials respond magnetically to electric fields and vise versa. High electric field experiments will seek a comprehensive understanding of this phenomenon, thereby leading to the ability to optimize materials for applications. The project will teach graduate students to use neutron scattering for condensed matter physics and attract young students to science through collaboration with a talent development high school.****TECHNICAL ABSTRACT****Materials governed by dynamic correlations present profound scientific challenges and opportunities for applications. This project seeks insights about such correlated matter through experiments on topical materials under extreme thermodynamic conditions. Quasi-two-dimensional magnets with competing interactions can remain in a dynamic correlated state at temperatures much less than the energy associated with the two particle interactions. Neutron scattering experiments under high uniaxial stress will be used to explore different low temperature phases of such systems. High pressure will be used to probe the quantum phase transition to long-range order from one- and two-dimensional quantum paramagnetic phases. Highly magnetized states of various quantum paramagnets will be probed in search of a field induced mixed phase analogous to that of type II superconductors. To understand and optimize multiferroic materials for applications, polarized neutrons will be used to explore the effects of high electric fields on the magnetic structure. The project will provide graduate education in the use of neutron scattering for condensed matter physics and seeks to attract more young people to science through collaboration with a talent development high school.

* 非技术摘要 * 冷却到足够低的温度，物质通常呈现固体晶体形式。然而，在极少数情况下，通常只在较高温度下发现的波动可以持续到绝对零度。这些材料提出了深刻的科学挑战，它们对外部刺激有不寻常的反应，这对应用很有意义。该项目旨在通过使其经受压力，应力，磁场和电场的极端条件来理解和控制强烈波动的物质。极端条件下驱动这种材料之间的强烈波动和常规的结晶相，从而揭示机制背后的异常性能。这些材料将通过中子散射进行探测，中子散射是一种提供原子尺度结构和运动详细信息的技术。实验将在包含相互作用的磁性离子的弦或平面的材料上进行，这些离子在环境条件下不会形成结晶磁性状态。有些材料对电场有磁性反应，反之亦然。高电场实验将寻求对这种现象的全面理解，从而能够优化材料的应用。该项目将教授研究生使用中子散射进行凝聚态物理学，并通过与人才培养高中的合作吸引年轻学生学习科学。技术摘要 * 动态相关性控制的材料提出了深刻的科学挑战和应用机会。该项目通过在极端热力学条件下对局部材料进行实验来寻求对这种相关物质的见解。具有竞争相互作用的准二维磁体可以在远低于与两个粒子相互作用相关的能量的温度下保持在动态关联状态。高单轴应力下的中子散射实验将用于探索这种系统的不同低温相。高压将用于探测从一维和二维量子顺磁相到长程有序的量子相变。各种量子顺磁体的高磁化状态将被探测，以寻找类似于II型超导体的场诱导混合相。为了理解和优化多铁性材料的应用，极化中子将用于探索高电场对磁结构的影响。该项目将提供关于将中子散射用于凝聚态物理学的研究生教育，并寻求通过与一所人才培养高中合作吸引更多的年轻人从事科学。