NMR Studies of the Competition Between Ground States in Correlated Electron Systems

相关电子系统中基态之间竞争的核磁共振研究

• 批准号: 9971530
• 负责人: Stuart Brown
• 金额: $ 27万
• 依托单位: University of California-Los Angeles
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-07-01 至 2002-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9971530&HistoricalAwards=false
• 关键词: NMR; Studies; Competition; Between; Ground

This project concerns the study of the physics of competing ground states in correlated electron systems. The properties of low temperature phases as well as the phase transition between different ground states are to be determined. Tuning external parameters, such as the pressure, disorder, stoichiometry and magnetic field will control the phase transitions. Specifically, phase transitions will be investigated in which antiferromagnetism competes with either superconductivity or an ordered Spin-Peierls phase. Additional attention will be given to the properties associated with the evolution from antiferromagnetism to superconductivity in the organic superconductor (TMTSF)2PF6, and the high-Tc superconductor lanthanum cuprate co-doped with Sr and Li. The Spin-Peierls/antiferromagnetic transition in the systems (TMTTF)2x, where x = PF6 or AsF6 will be examined. The primary probe is NMR spectroscopy, under varied but controlled conditions of high pressure and high magnetic fields in order to access the different phases. The Principal Investigator will conduct this research in collaboration with graduate and undergraduate students. The students will be involved in the design, planning and execution stages of the experiments. They will learn a variety of technical skills in areas of current research and are thereby trained for employment in fields of technological importance during the next few decades of the 21st Century. %%%This project is concerned with the investigation of how novel materials can coexist in different physical states and how transitions between these states compete with one another. The materials in question are those that exhibit, for example, superconductivity and other phenomena which are intensively studied for their own intrinsic scientific interest as well for their potential applications in new technological devices. Graduate and undergraduate students, as well as postdoctoral research associates participate in this work and are thereby trained in forefront areas of condensed matter physics and materials science. They are thus prepared to enter the scientific/technical workforce of the future.***

这个项目涉及相关电子系统中竞争基态的物理学研究。低温相的性质以及不同基态之间的相变需要确定。调节外部参数，如压力、无序度、化学计量和磁场，将控制相变。具体来说，将研究反铁磁性与超导性或有序自旋-佩尔斯相竞争的相变。本文将进一步关注有机超导体（TMTSF）2PF6和高tc超导体铜酸镧共掺杂Sr和Li的反铁磁性向超导性演变的相关性质。系统（TMTTF）2x中的自旋-佩尔/反铁磁跃迁，其中x = PF6或AsF6将被检查。主要探针是核磁共振波谱，在高压和高磁场的不同但可控的条件下，以获得不同的相。首席研究员将与研究生和本科生合作进行这项研究。学生将参与实验的设计、计划和执行阶段。他们将学习当前研究领域的各种技术技能，从而为在21世纪未来几十年的重要技术领域就业提供培训。这个项目关注的是研究新材料如何在不同的物理状态下共存，以及这些状态之间的转换如何相互竞争。所讨论的材料是那些表现出，例如，超导性和其他现象的材料，这些现象由于其内在的科学兴趣以及它们在新技术设备中的潜在应用而被深入研究。研究生和本科生，以及博士后研究助理参与这项工作，从而在凝聚态物理和材料科学的前沿领域进行培训。因此，他们准备进入未来的科学/技术劳动力