RUI: NMR Studies of Hidden Order and Quantum Criticality

非技术性这是一个实验性的凝聚态项目。它专注于研究相变和发现物质新状态的可能性。这项研究使用的材料被命名为“电子相关系统”。它们大多是金属间化合物，其热学和导电性与铜或银等普通金属有很大不同。与电子相关的材料是当前科学和技术领域的研究热点，因为它们可以以多种状态被发现。例如，它们可以显示超导、磁性、反铁磁性、四极有序、巨磁电阻，以及本项目特别感兴趣的隐藏有序和所谓的“非费米液体行为”。核磁共振技术将被用来研究URu2Si2和UCu5-xNix的性质，目的是了解它们异常行为的本质。本科生和硕士生将接受磁共振、射频电子学、低温技术和计算机接口技术方面的培训。这个项目的一个方面与K-12教育有关。洛杉矶地区的一些教师将有机会加深他们对小学一级教授的科学标准和概念的理解，并将学习将围绕这些标准加强教学的实验技术。合作将包括在小学现场和加州州立大学洛杉矶分校举行的会议，以及学生的课程旅行。技术上，这个实验凝聚态项目将专注于研究与电子相关的材料的相变和固有的不均匀性质。它的目的是表征两种特定材料及其化合物中局部磁场和电场梯度分布的静态和动态特性：URu2Si2和UCu1-xNix。前者经历了一个相变，其中包含一个未知的序参数。提出了四极、八极、自旋手性和轨道反铁磁性等可能的有序状态。核磁共振将被用来探测内场及其局域分布，目的是阐明真实的有序参数。UCu4Ni和x=1附近的其他成分在设计上是无序的，并呈现出与量子临界点相关的非费米液体行为。核磁共振将被用来研究磁无序，并阐明它或量子临界性在多大程度上对低温下的异常行为负责。一个要解决的主要问题是量子临界现象的普遍性，因为有序和无序的非费米液体系统在绝对零度附近的行为似乎非常相似。该项目有一个K-12教育部分，洛杉矶地区的教师将加深他们对小学一级教授的科学标准和概念的理解，并学习将加强教学的实验技术。将在小学场地和加州州立大学洛杉矶分校举行会议，并为学生进行课程旅行。

Non TechnicalThis is an experimental condensed matter project. It concentrates on the investigation of phase transitions and the possibility of discovering new states of matter. The materials used for this investigation are named "electron-correlated systems." These are mostly inter-metallic compounds whose thermal and conductance properties are very different from normal metals such as copper or silver, for instance. Electron-correlated materials are of current interest for science and technology because of the many states in which they can be found. For instance, they can display superconductivity, magnetism, antiferromagnetism, quadrupolar ordering, colossal magnetoresistance, and of particular interest for this project, hidden order and the so-called "non-Fermi liquid behavior." Nuclear-magnetic resonance techniques will be used to study the properties of URu2Si2 and UCu5-xNix with the goal of understanding the nature of their unusual behavior. Undergraduate and masters-level students will be trained in the techniques of magnetic resonance, radio-frequency electronics, cryogenics, and computer interface. One aspect of this project is related to K-12 education. Some Los Angeles area teachers will have a chance to deepen their understanding of the science standards and concepts taught at the elementary school level and will learn about experimental techniques that will enhance instruction around those standards. The collaboration will involve meetings at the elementary school sites and Cal State L.A., as well as curricular trips for the students.TechnicalThis experimental condensed matter project will concentrate on the study of phase transitions and intrinsic inhomogeneous properties in electron-correlated materials. It will aim to characterize the static and dynamic properties of local magnetic and electric-field-gradient distributions in two specific materials and their compounds: URu2Si2 and UCu1-xNix. The former undergoes a phase transition involving an as-yet unknown order parameter. Among the possible ordered states being proposed are quadrupolar, octupolar, spin chiral, and orbital antiferromagnetism. NMR will be used to probe the internal fields and their local distributions with the goal of elucidating the true order parameter. UCu4Ni and other compositions near x=1 are disordered by design and present non-Fermi liquid behavior related to a quantum critical point. NMR will be used to study the magnetic disorder and to elucidate to what extent it or quantum criticality is responsible for the unusual behavior at low temperatures. One main question to address is that of the universality of quantum critical phenomena, since both ordered and disordered non-Fermi liquid systems seem to behave very similarly near absolute zero. This project has a K-12 education component in which Los Angeles area teachers will deepen their understanding of the science standards and concepts taught at the elementary school level and learn experimental techniques that will enhance instruction. Meetings at the elementary school sites and Cal State L.A. as well as curricular trips for the students will be carried out.