NMR Studies of Field-Induced Phases in Molecular Solids

* 技术摘要 * 在这个项目的过程中，固态磁共振技术将被用来解决与新的磁场感应相有关的问题。要研究的系统是选定的分子超导体和绝缘体与非磁性基态，每一个表现出场诱导相或现象与未探索和未知的属性。这些包括层状超导体中的高场相，电荷密度波/自旋-佩尔斯耦合系统中的高场相，以及候选自旋-液体系统中的场诱导现象或相。确定新的秩序形式，有时是期望和长期寻求的，是该项目的主要目标，并相应地选择问题和系统。在相关的努力中，将探讨电荷有序和挫折之间的关联，目标是确定一条新的自旋液体材料的路径，使用压力作为调谐参数。为这些研究选择的分子晶体的性质是唯一适用于解决的问题。将在NMR光谱和弛豫实验的结果中寻找相变的特征，并酌情进行补充物理性质测量。磁共振通常是这些问题的理想探针，因为它与所需的极端条件兼容，并且因为它是通过超精细耦合对电子环境敏感的局部探针。如果可能的话，研究将在我们在加州大学洛杉矶分校的实验室进行，并在国家高磁场实验室（NHMFL）进行需要更高磁场的工作。该项目将支持研究生和本科生的努力，他们将为学术或工业实验室的进一步工作做好充分准备。非技术摘要 * 该项目的主要目的是创造和研究在极端条件下产生的物质的新相，如高磁场，低温和高压。选择特定的问题和系统是因为显着的物理性质，往往出现在系统与强电子-电子相互作用和低维系统。我们将研究的一个例子是通过强磁场稳定新的超导相。改变非热参数（磁场和压力）允许连续调整重要的相互作用，这有时会导致涌现的属性和相位，以及提供可以研究材料的条件。大部分工作将在我们加州大学洛杉矶分校的实验室和国家高磁场实验室使用固态核磁共振（NMR）的方法进行。NMR方法对所研究的原子核位置处的电子环境局部敏感。研究生和本科生都将进行大部分的实验计划，并在这样做将开发在低温，高压技术和高功率射频方法的专业知识，以及材料的全面知识。每个人都将为材料相关研究或工程实验室的进一步工作做好充分准备。

****Technical Abstract****In the course of this project, solid state magnetic resonance techniques will be employed to address questions related to novel magnetic field-induced phases. The systems to be studied are selected molecular superconductors and insulators with non-magnetic ground states, each exhibiting field-induced phases or phenomena with unexplored and unknown properties. These include high-field phases in layered superconductors, in a charge density wave/Spin-Peierls coupled system, and field-induced phenomena or phases in a candidate spin-liquid system. Identification of new forms of order, sometimes expected and long-sought for is the primary aim of the project, and the problems and systems are chosen accordingly. In a related effort, an association between charge ordering and frustration will be explored, with the goal of identifying a pathway to new spin liquid materials using pressure as the tuning parameter. The properties of the molecular crystals chosen for these studies are uniquely applicable to the problems addressed. Signatures for phase transitions will be looked for in the results of NMR spectroscopy and relaxation experiments, and complimentary physical properties measurements will be undertaken as appropriate. Magnetic resonance is often an ideal probe for these problems, because of its compatibility to the required extreme conditions, and because it is a local probe sensitive to the electronic environment through the hyperfine coupling. When possible, the research will be conducted in our laboratory at UCLA, and at the National High Magnetic Field Laboratory (NHMFL) for work requiring higher magnetic fields. The project will support efforts carried out by graduate and undergraduate students alike, who will be well-prepared for further work in academic or industrial laboratories.****Non-Technical Abstract****The primary aim of this project is the creation and investigation of novel phases of matter produced under extreme conditions, such as high magnetic fields, low temperatures, and high pressures. The specific problems and systems are chosen because of remarkable physical properties that tend to emerge from systems with strong electron-electron interactions and in low-dimensional systems. One such example we will be investigating is the stabilization of novel superconducting phases by high magnetic fields. Varying the non-thermal parameters (magnetic fields and pressure) allow for a continuous tuning of the important interactions, which sometimes leads to emergent properties and phases, as well as providing the conditions under which the material can be studied. Much of the work will be carried using the methods of solid state nuclear magnetic resonance (NMR) at our laboratory at UCLA and at the National High Magnetic Field Laboratory. NMR methods are locally sensitive to the electronic environment at the site of the nucleus under study. Both graduate and undergraduate students will carry out much of the experimental program, and in so doing will develop expertise in cryogenics, high-pressure techniques, and high-power radiofrequency methods, as well as a comprehensive knowledge of materials. Each will be well-prepared for further work in materials-related research or engineering laboratories.