RUI: Pressure And Chemical Modulation Of Nanoscale Magnetic Interactions In Metal-Organic Polymers

RUI：金属有机聚合物纳米级磁相互作用的压力和化学调节

• 批准号: 1005825
• 负责人: Jamie Manson
• 金额: $ 26.5万
• 依托单位: Eastern Washington University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-09-01 至 2013-10-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1005825&HistoricalAwards=false
• 关键词: RUI; Pressure; Chemical; Modulation; Nanoscale

****NON-TECHNICAL ABSTRACT****Superconductors, materials which conduct electricity without any loss due to resistance, have the potential to revolutionize the energy demands of our society in the future. However, scientists need to increase the working temperatures of the superconductors in order for them to be useful. Despite much study, in many instances the mechanism behind the superconducting behavior remains a mystery. In an attempt to develop a better understanding of their complex behaviors, this award supports a project aiming to synthesize and characterize molecular materials that mimic the magnetic properties of oxide and pnictide superconductors, two classes of superconductors that may work at higher temperatures. The challenge in directly studying such systems lies in the large magnetic interactions that exist between the magnetic sites they contained. Through a variety of chemical methods, attempts will be made to reduce the scale of these interactions by controlling the molecular assembly of model compounds using particular combinations of chemical bonds. This structural control will enable a systematic approach to vary distances between atoms, the number of magnetically-active electrons, and other properties of the material. The application of pressure may lead to other unusual discoveries. The materials discovery effort will be complemented by extensive characterization and theoretical work. The highly collaborative nature of this project makes use of several national and international user facilities and will provide unique opportunities for the undergraduate students to travel to facilities to participate in the experiments, as well as to attend professional conferences. Undergraduate student involvement in every aspect of the project will stimulate the students? growth and enthusiasm as young scientists, as well as provide them with the necessary background to begin graduate work in the future or to go on to careers in the physical sciences. This research project receives support from the Division of Materials Research and the Chemistry Division.****TECHNICAL ABSTRACT****This award to a Predominately Undergraduate Institution will support research focusing on the design, synthesis, and characterization of low-dimensional (1- and 2D) quantum magnets, in particular square lattices, as they may mimic the structural and magnetic properties of analogous cuprate and iron-pnictide superconductors. Using specific combinations of coordinate covalent bonds and strong hydrogen bonds, the molecular positioning of components will be controlled and tuned and the magnitude/sign of the intralayer (J) and interlayer (J') magnetic interactions and their relative ratio (J'/J) will be systematically varied. The magnetic tunability of the systems will be achieved by: (a) ion-exchange (either positive or negative), (b) chemical doping, (c) application of hydrostatic or chemical pressure (i.e., isotopic substitution) and (d) co-ligand variation. Control of inter- and intralayer couplings will enable the modulation of the exchange anisotropy, critical temperatures (TN), and critical magnetic fields (Bc). In addition, the single-ion anisotropy in these systems will be manipulated by modifying the spin quantum number. The materials discovery effort will be complemented by extensive characterization and theoretical work. Magnetic-field and/or pressure-induced quantum criticality may lead to unusual phases, such that abrupt changes in behavior can occur due to instabilities in the magnetic system which ultimately drive phase transitions. Undergraduate student involvement in every facet of the project will stimulate their growth and enthusiasm as young scientists, as well as provide them with the necessary background to begin graduate work in the future or to go on to careers in the physical sciences. This research project receives support from the Division of Materials Research and the Chemistry Division.

* 非技术性摘要 * 超导体是一种导电材料，不会因电阻而产生任何损失，有可能在未来彻底改变我们社会的能源需求。然而，科学家们需要提高超导体的工作温度，才能让它们发挥作用。 尽管进行了大量研究，但在许多情况下，超导行为背后的机制仍然是一个谜。为了更好地理解它们的复杂行为，该奖项支持一个旨在合成和表征分子材料的项目，这些材料模拟氧化物和磷属元素化物超导体的磁性，这两类超导体可能在更高的温度下工作。直接研究这些系统的挑战在于它们所包含的磁性位点之间存在的大的磁相互作用。通过各种化学方法，将尝试通过使用化学键的特定组合控制模型化合物的分子组装来减小这些相互作用的规模。这种结构控制将使系统的方法来改变原子之间的距离，磁活性电子的数量和材料的其他属性。 施加压力可能会导致其他不寻常的发现。材料发现工作将得到广泛的表征和理论工作的补充。该项目的高度协作性利用了几个国家和国际用户设施，并将为本科生提供独特的机会前往设施参加实验，以及参加专业会议。本科生参与项目的每一个环节都会激发学生的学习兴趣吗？这将有助于年轻科学家的成长和热情，并为他们提供必要的背景知识，以便他们开始未来的研究生工作或继续从事物理科学的职业生涯。该研究项目得到了材料研究部和化学部的支持。*技术摘要 **** 该奖项授予一个主要的本科院校，将支持研究重点放在低维（1-和2D）量子磁体的设计，合成和表征，特别是方形晶格，因为它们可以模仿类似的铜酸盐和铁磷族化合物超导体的结构和磁性。使用配位共价键和强氢键的特定组合，将控制和调节组分的分子定位，并且将系统地改变层内（J）和层间（J '）磁相互作用的大小/符号及其相对比率（J'/J）。系统的磁可调谐性将通过以下方式实现：（a）离子交换（正或负），（B）化学掺杂，（c）流体静压或化学压力的施加（即，同位素取代）和（d）共配体变化。层间和层内耦合的控制将使得能够调制交换各向异性、临界温度（TN）和临界磁场（Bc）。此外，在这些系统中的单离子各向异性将被操纵通过修改自旋量子数。材料发现工作将得到广泛的表征和理论工作的补充。磁场和/或压力诱导的量子临界性可能导致不寻常的相位，使得由于磁系统中的不稳定性而可能发生行为的突然变化，这最终驱动相变。 本科生参与该项目的各个方面将刺激他们的成长和热情作为年轻的科学家，以及为他们提供必要的背景开始研究生工作在未来或继续在物理科学的职业生涯。该研究项目得到了材料研究部和化学部的支持。