CAREER: Warm Quantum Materials: Harnessing Exotic Quantum Properties at High Temperatures

非技术摘要：超导是凝聚态物理中最深刻的现象之一，它具有完全无电阻的特性。在常温下或在常压下达到接近室温的超导电性状态是开创性的。压力已被证明是制造新材料(如超导体)中最通用的调节参数。富氢材料，模仿难以捉摸的氢的固体金属相，可以在低得多的压力下金属化，在低得多的压力下促进高T_c超导。该项目的主要目标是在常压下合成新型富氢、室温或更高温度的超导材料，用于实际应用，如先进的电网、新的交通、医学成像和扫描技术，如核磁共振和心磁图，以及用于数字逻辑和存储器件技术的更快、更高效的电子设备。该项目还为高压实验提供了一个重要的研究基础设施，有能力解决材料科学中的各种问题。首席调查员将创建教育媒体，以支持世界各地的教学和学生学习。得到直接支持的群体包括：研究生能够使用大型用户设施并学习必要的研究技能；当地高中教师与首席调查员合作直接应用课堂概念；第一代大学、低收入和代表性不足的少数族裔学生的研究机会；以及改进和利用聋人社区可用的资源。技术摘要：量子材料的性质对压力等外界刺激异常敏感，这些刺激会产生奇异的、往往是前所未有的性质。在一类新的致密、富氢的材料--超氢材料中发现了高T_c超导电性，重新激发了人们对室温或温超导电性的长期追求。超氢化物依赖于氢分子的解离作用，氢分子解离提供了费米能级附近的能态所需的额外电子。然而，到目前为止，理论和实验研究主要集中在二元超氢化合物上。本项目所设想的努力代表了一个自然和及时的研究方向，以发现和了解新型三元和四元超导体的结构、化学键和稳定性，这些超导体的T_c等于或高于室温，并通过成分调整，在保持超导性能的同时降低转变压力。此外，为了了解这些热超导体的量子性质，在高压实验中主要需要绝对温度测量。为了弥补这一需求，氮空位中心提供了一种新的方法来潜在地确定压缩材料在Mbar范围内的原位温度测量，这将是革命性的。仔细的热测量可能会增加测量超导超氢化物热容的能力，这是一种更好的超导测试。这项工作将使研究团队能够更广泛地了解超导，包括稳定性，并因此为变革性技术设计一类新的暖量子材料。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Non-technical Abstract:Superconductivity is one of the most profound phenomena in condensed matter physics and has the property of complete absence of electrical resistance. Achieving a state of superconductivity at room temperature or near room temperature at ambient pressure is groundbreaking. Pressure has been proven to be the most versatile tuning parameter in making novel materials, such as superconductors. Hydrogen-rich materials, mimicking the elusive solid metallic phase of hydrogen, can be metalized at much lower pressures, promoting high-Tc superconductivity at much lower pressures. The primary goal of this project is to synthesize novel hydrogen rich, room temperature or above room temperature superconducting materials at ambient pressure for practical applications, such as advanced power grids, new transportation, medical imaging, and scanning techniques such as MRI and magnetocardiography, and faster, more efficient electronics for digital logic and memory device technology. The project also provides an important research infrastructure for high pressure experiments with capabilities of addressing a diverse set of problems in materials science. The principal investigator will create educational media to support teaching and student learning all over the world. Groups receiving direct support include graduate students gaining access to large user facilities and learning necessary research skills; local high school teachers collaborating with the principal investigator on direct application of classroom concepts; research opportunities for first-generation college, low-income, and underrepresented minority students; and improving and building upon resources available to the Deaf community. Technical Abstract:The properties of quantum materials are anomalously sensitive to external stimuli such as pressure, which give rise to exotic and often unprecedented properties. The long-standing quest for room-temperature or warm superconductivity has been reinvigorated by the discovery of high Tc superconductivity in a new class of dense, hydrogen-rich materials—superhydrides. The superhydrides rely on the role of the dissociation of the hydrogen molecules, which provide the extra electrons needed in energy states near the Fermi level. However, thus far, theoretical and experimental studies are mainly focused on binary superhydrides. The efforts envisioned in this project represent a natural and timely research direction to discover and understand structure, chemical bonding, and stability of novel ternary and quaternary superconductors with Tc comparable to or higher than room temperature and via compositional tuning, lowering the transition pressure while preserving the superconducting properties. Furthermore, in order to understand the quantum nature of these hot superconductors, there is a major need for absolute temperature measurements in high pressure experiments. To remedy this need, Nitrogen vacancy centers provide a new way to potentially determine the in-situ temperature measurement for compressed materials into the Mbar range, which would be revolutionary. Careful thermal measurements would likely increase the ability to measure the heat capacity on superconducting superhydrides, which is a superior test for superconductivity. The work will allow the research team to obtain insight into superconductivity more broadly including the stabilities, and as such, to the design of a new class of warm quantum materials for transformative technologies.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.