Pressure Tuning of Competing Quantum States

非技术性质不同状态之间的转变--从固体到液体再到气体，从导体到绝缘体--是常见的。在绝对零度温度下，不同的物理学进入。量子力学发挥着核心作用，改变了为经典跃迁制定的普遍反应。这可能导致材料的光学响应、器件的电学特性或存储材料的磁容量方面的新可能性。该项目从三个相关领域探索模型系统的量子特征：解析磁性和超导电性之间的合作与竞争，描绘当电子片被置于非常高的磁场中时所获得的物质的新状态，以及破译绝缘体可以转变为金属的方式。在每一种情况下，这项研究都利用了钻石砧座技术获得日常技术之外的压力和传输高能X射线的能力。广泛的技术，从同步加速器的X射线散射到实验室的电测量，以及将物理、化学和材料科学应用于这些研究的必要性，为学生在工业、国家实验室或学术界的职业生涯培养了良好的人才。将研究视角引入教育是另一个重点，包括与STEM教师和普通公众的联系。技术简介量子相变的影响可以感受到令人惊讶的高温。许多技术进口的材料表现出不同寻常的电子、光学和磁性，这被归因于量子临界点的紧密接近。然而，复杂的材料性质与相互竞争的基态混为一谈，使得人们很难分辨出本质的物理学。此外，如果没有温度作为变量，对量子临界点的研究很难接近经典临界现象实验的精确度。这个项目结合了对纯材料的高分辨率研究，这些材料使用压力调节到可到达的量子临界点，以揭示磁性、无序、相关材料和量子相变的基本方面。其中包括调制自旋有序和超导电性之间的竞争，正方形晶格上自旋单重态的基本量子磁性，以及相关材料中从绝缘体到金属的转变。从x射线散射到磁传输的各种技术，为学生在工业、国家实验室或学术界的职业生涯提供了良好的培训。对凝聚态物理学家和地球物理学家来说，钻石砧座技术的进步都很重要。支持STEM教师并帮助他们制定课程是当务之急。

NON-TECHNICAL ABSTRACTTransitions between different states - solid to liquid to gas, conductor to insulator - are common occurrences. At the absolute zero of temperature, different physics enters. Quantum mechanics plays a central role, altering the universal response that has been mapped out for classical transitions. This can lead to new possibilities in the optical response of materials, the electronic character of devices, or the magnetic capacity of storage materials. This project probes the quantum characteristics of model systems in three related arenas: parsing the cooperation and competition between magnetism and superconductivity, delineating the new states of matter accessed when sheets of electrons are placed in very high magnetic fields, and deciphering the way in which an insulator can be transformed into a metal. In each case, the research takes advantage of the ability of diamond anvil cell technology to access pressures outside of everyday techniques and to transmit high energy x-rays. The wide array of techniques, from x-ray scattering at a synchrotron to electrical measurements in the laboratory, and the necessity to apply physics, chemistry and materials science to these studies, trains students well for careers in industry, the national laboratories, or academia. Bringing research perspectives to education is another emphasis, including connections with STEM teachers and the general public. TECHNICAL ABSTRACTThe effects of a quantum phase transition can be felt up to surprisingly high temperatures. Many materials of technological import demonstrate unusual electronic, optical, and magnetic properties that have been ascribed to the close proximity of quantum critical points. However, complex materials properties, conflated with competing ground states, have made it difficult to discern the essential physics. Moreover, without temperature as a variable, studies of quantum critical points are hard pressed to approach the exactitude that has become the hallmark of experiments on classical critical phenomena. This project combines high-resolution studies of pure materials tuned to accessible quantum critical points using pressure to reveal fundamental aspects of magnetism, disorder, correlated materials, and quantum phase transitions. These include the competition between modulated spin order and superconductivity, the fundamental quantum magnetism of spin singlets arranged on a square lattice, and the transition from insulator to metal in a correlated material. The wide array of techniques, from x-ray scattering to magnetotransport, trains students well for careers in industry, the national laboratories, or academia. Advances in diamond anvil cell technology are important for condensed matter physicists and geophysicists alike. Supporting STEM teachers and helping them develop curricula is a priority.