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

本计画研究关联电子系统中竞争基态的物理。 低温相的性质以及不同基态之间的相变将被确定。 调整外部参数，如压力，无序，化学计量和磁场将控制相变。 具体而言，相变将被调查，其中反铁磁性竞争与超导性或有序的自旋佩尔斯相。额外的注意力将被给予与有机超导体（TMTSF）2 PF 6，和高Tc超导体铜酸镧共掺杂Sr和Li的从反铁磁性到超导电性的演变相关的属性。 研究了（TMTTF）2x（x = PF_6或AsF_6）体系的自旋-Peierls/反铁磁相变。 主要的探针是NMR光谱，在高压和高磁场的变化但受控的条件下，以访问不同的相。主要研究者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，规划和执行阶段。 他们将学习当前研究领域的各种技术技能，从而在21世纪世纪的未来几十年中接受技术重要性领域的就业培训。 该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，这些材料因其自身内在的科学利益以及其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/技术劳动力队伍。

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.***