Novel Hydrogen-rich Materials at High Pressures: Possible Route to Room Temperature Superconductivity

摘要：超导体无电阻导电，是凝聚态物理中最令人着迷的材料之一。实现室温或接近室温的超导状态将彻底改变我们的能源生产和运输系统，并将促进经济增长和生活质量。压力已被证明是制造具有奇异特性（如超导性）的新材料时最通用的调谐参数。固体金属氢，氢的高压相，预测具有室温超导性。然而，这需要极大的压力。富氢材料，模拟氢的难以捉摸的固体金属相，可以在更低的压力下导致高tc超导。本项目的主要目标是在高压温度条件下合成新型富氢超导材料，并探索其室温超导性的可能性。该项目的进展可以为超导机制提供更清晰的信息。反过来，它可能使我们能够在环境压力下大量设计新的超导材料。通过全面的外展方法，首席研究员将招募并指导高中生提供经验，以培养他们的科学探究和沟通技巧。外展的目标是接触那些在科学、技术、工程和数学领域代表性不足的学生。首席研究员与罗彻斯特大学的麦克奈尔项目合作，该项目的任务是增加低收入、第一代和未被充分代表的少数民族本科生攻读博士学位的人数。技术摘要：超导性一直是凝聚态物理中最神秘的量子相之一。固体金属氢理论上具有高德拜温度和强电子-声子耦合，这是高tc声子介导超导性所必需的。然而，这需要极大的压力。作为替代方案，富氢材料，模拟氢的难以捉摸的固体金属相，可以在更低的压力下金属化，在费米能级上提供大的氢衍生电子密度和响应氢原子运动的电子结构的大修改（电子-声子耦合）。本研究的主要目标是合成已知或可能表现出高Tc超导性的新型富氢超导材料。最先进的高压和高温技术，激光光谱学和低温技术结合新的输运测量被用于合成和探测高温超导性。这个项目的成功说明超导机制更加清晰。反过来，它可能使研究小组获得在环境压力下大量设计新型超导材料的见解。该项目还为研究生提供尖端纳米制造技术和大型用户设施（如同步加速器和中子设施）的实践经验。此外，该项目还为当地高中生提供暑期实习机会，首席研究员与罗切斯特大学的麦克奈尔项目合作，该项目的使命是增加低收入、第一代和未被充分代表的少数民族本科生攻读博士学位的人数，招募和指导学生。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值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: Superconductors, which conduct electricity without resistance, are among the most fascinating materials in condensed matter physics. Achieving a state of superconductivity at room temperature or near room temperature will revolutionize our energy production and transportation system and will enhance economic growth and quality of life. Pressure has been proven to be the most versatile tuning parameter in making novel materials with exotic properties such as superconductivity. Solid metallic hydrogen, the high pressure phase of hydrogen, is predicted to have room temperature superconductivity. However, it requires extreme pressure. Hydrogen-rich materials, mimicking the elusive solid metallic phase of hydrogen, may lead to high-Tc superconductivity at much lower pressures. The primary goal of this project is to synthesize novel hydrogen-rich superconducting materials at high pressure temperature conditions and explore their possible room temperature superconductivity. Progress on this project can provide greater clarity regarding superconducting mechanisms. In turn, it may allow us to obtain insight into designing new superconducting materials in large quantities at ambient pressure. Through a comprehensive outreach approach, the principal investigator will recruit and mentor high school students to provide experiences to foster their scientific inquiry and communication skills. A goal of the outreach is to reach students who are underrepresented in the areas of science, technology, engineering, and mathematics. The principal investigator works with the University of Rochester's McNair program, whose mission is to increase the numbers of low-income, first generation, and underrepresented minority undergraduates who pursue PhD degrees.Technical Abstract: Superconductivity has been one of the most arcane quantum phases in condensed matter physics. Solid metallic hydrogen is theorized to have the high Debye temperature and strong electron-phonon coupling that are necessary for high-Tc phonon-mediated superconductivity. However, it requires extreme pressure. As an alternative, hydrogen-rich materials, mimicking the elusive solid metallic phase of hydrogen, can be metalized at much lower pressures, providing large hydrogen-derived electronic density of states at the Fermi level and large modifications of the electronic structure in response to the motion of hydrogen atoms (electron-phonon coupling). The primary goal of this research is to synthesize novel hydrogen rich superconducting materials that are either known or likely to exhibit high Tc superconductivity. State-of-the-art high pressure and high temperature techniques, laser spectroscopy, and low temperature techniques in conjunction with novel transport measurements are used to synthesize and probe high temperature superconductivity. Success on this project elucidates greater clarity in superconducting mechanisms. In turn, it may allow the research team to obtain insight into designing new superconducting materials in large quantities at ambient pressure. The project also provides graduate students hands-on experience with cutting-edge nano-fabrication technologies and large user facilities, such as synchrotron and neutron facilities. In addition, the project offers summer internships to local high school students, and the principal investigator works with the University of Rochester's McNair program, whose mission is to increase the numbers of low-income, first generation, and underrepresented minority undergraduates who pursue PhD degrees, to recruit and mentor students.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.