CAREER: Visualizing Emergent Electronic States Near Quantum Phase Transitions

非技术摘要：非常规超导是量子物质的一种令人着迷的状态。它的绝对零电阻率保证了清洁能源传输和无摩擦磁悬浮运输的未来。三十年来，超导性一直是科学界面临的挑战。与电子自由移动的简单金属不同，在非常规超导体中，电子大多被限制在二维平面中。这种限制，加上它们之间更强的相互作用，造成了电子的“交通堵塞”。在外部，改变电子的数量会导致物质的各种新状态，如超导性和奇异的电子模式。目前还不清楚这些不同的电子状态是共存还是竞争。利用扫描隧道显微镜（一种局部可视化电子的实验技术）和共振x射线散射（一种全局电子态的实验探针），研究小组旨在研究这些电子态如何在各种相关材料系统中出现。需要回答的一个重要问题是，外部调优如何在局部破坏一个有序状态并增强另一个有序状态。该项目旨在推进我们对超导性的基本理解，并提供提高其转变温度的方法。这项研究的教育目标是通过利用主要研究者的研究工具的外展活动产生的，这些活动将通过现场演示和动手实验来震惊和激励K-12学生，并为本科生和研究生提供明确的教育和培训。技术文摘：识别量子相变附近的对称性破缺态仍然是强相关电子系统的一个关键目标。一个具有挑战性的目标是对涌现的超导性的微观理解。这一挑战的核心是各种电子态的局部共存，如向列态、电荷态和轨道有序，它们抢占、促进或与超导性交织在一起。探测和可视化这些有序态的微观起源并有意地调整它们是理解和控制超导性的关键目标。该研究计划旨在可视化和调整d-和f-相关电子系统中接近量子相变的对称性破缺状态。研究小组使用了一种新的方法，可以单轴应变这些材料系统，并通过扫描隧道显微镜和共振x射线散射的光谱成像来可视化它们在电子态密度中的响应。该研究计划的目标是发现和理解相关材料系统中可能促进、增强或扭转超导性的物质的新相。这项研究通过旨在惊奇和激励K-12学生的外展活动产生了自然更广泛的影响。其中一些活动包括现场演示和动手实验，如低温冷却、超导悬浮和运输，这些活动将在宾厄姆顿足球圆顶体育场、科普尼克天文台和科学中心以及当地小学进行。一门研究生水平的凝聚态实验技术课程由主要研究者开发，为本科生和研究生提供明确的教育和培训。

Non-technical abstract:Unconventional superconductivity is a fascinating state of quantum matter. Its absolute zero resistivity promises the future of clean energy transmission and magnetically-levitated transportation without friction. Superconductivity has been challenging the scientific community for three decades. Unlike in simple metals, where electrons move freely, in unconventional superconductors they are mostly confined in two dimensional planes. This restriction, together with their mutual stronger interaction, create a "traffic jam" of electrons. Externally, altering the number of the electrons leads to various novel states of matter, such as superconductivity and exotic electronic patterns. It remains unclear whether these different electronic states coexist or compete. Using a scanning tunneling microscope, an experimental technique that locally visualizes the electrons, and resonant x-ray scattering, an experimental probe of global electronic states, the research team aims to investigate how these electronic states emerge in various correlated material systems. An important question to be answered is how external tuning can locally destroy one ordered state and enhance another. The project is designed to advance our fundamental understanding of superconductivity and provide means for enhancing their transition temperatures. Educational goals result from this research through outreach activities utilizing the principle investigator's research tools that will amaze and inspire K-12 students with live-demonstrations and hands-on experimentations as well as provide explicit education and training of undergraduate and graduate students.Technical abstract:Identifying broken symmetry states near quantum phase transitions remains a key objective of strongly correlated electron systems. A challenging goal is the microscopic understanding of emergent superconductivity. Central to this challenge is the local coexistence of various electronic states, such as nematic, charge, and orbital ordering that preempt, promote, or are intertwined with superconductivity. Probing and visualizing the microscopic origin of these ordered states and deliberately tuning them is the key objective towards understanding and controlling superconductivity. The research program aims to visualize and tune broken symmetry states in d- and f-correlated electron systems near quantum phase transitions. The research team uses a new approach that enables to uniaxially strain these material systems and visualize their response in the electronic density of states through spectroscopic imaging with the scanning tunneling microscope and resonant x-ray scattering. The research program's goal is to discover and understand novel phases of matter in correlated material systems that may promote, enhance, or twist superconductivity. Natural broader impacts result from this research through outreach activities that aim to amaze and inspire K-12 students. Some of these activities involve live demonstrations and hands-on experimentations, such as cryogenic cooling, superconducting levitation and transportation to be performed at the Greater Binghamton Soccer Dome, the Kopernik Observatory & Science Center, and local elementary schools. A graduate level course on experimental techniques in condensed matter is developed by the principle investigator that provides explicit education and training for undergraduate and graduate students.