Optical properties of the superconducting hydrides and of topological materials

发现在室温下具有超导性的材料仍然是凝聚态物理学的一个非常理想的目标。它将彻底改变核磁共振成像仪在医院的使用，电力传输的电网和高速旅行的磁悬浮。最近在150 GPa压力下H3S中发现临界温度Tc = 200 K的超导性，以及随后的光学证据表明驱动机制是电子-声子相互作用，这是一个巨大的飞跃。对其他氢化物和相关材料的系统研究，其中一些是在环境压力下进行的，是这一研究领域的核心。我们建议提供理论支持来指导实验人员进行这项研究，并解释他们的结果，特别是因为它涉及到机制以及如何操纵它来实现更高的Tc值。在这方面，光学已被证明是一项强大的技术，我们是世界专家。凝聚态物理最近的第二个重要发展是拓扑材料的发现，它引入了新的概念和思考半金属的新方法。它使我们迅速认识到拓扑在为电子系统提供全新功能方面的重要性。这对光电器件、自旋电子学、磁存储器、太阳能电池、水过滤、量子计算以及更广泛的通信具有变革性影响。这一领域的新材料被迅速发现，部分原因是理论的进步。强大的新数值技术使我们能够准确地预测电子结构和隐含的性质。我们建议计算新的拓扑半金属的选择性质，包括Weyl和Dirac材料，因为它们是在实验室中发现的，目的是增加对新的和独特的性质可能的理解。在固体系统中已经发现了新的Weyl费米子，在高能粒子物理中没有对应的。因此，人们正在发现可能影响未来技术的基本新物理学。拟议的研究计划还将为研究生提供先进的数学、数值和计算技术方面的扎实培训，这些技能非常理想，可转移到许多其他领域。

The discovery of materials that superconduct at room temperature remains a highly desirable goal of condensed matter physics. It would revolutionize the use of MRI imagers in hospitals, the electrical grid for power transmission and magnetic levitation for high speed travel. The recent discovery of superconductivity with a critical temperature Tc = 200 K in H3S under 150 GPa pressure, and subsequent optical evidence that the driving mechanism is the electron-phonon interaction represents a quantum leap forward. The systematic study of other hydrides and related materials, some at ambient pressure is central to this area of research. We proposed to provide theoretical support to guide experimentalists in this search and to interpret their results particularly as it relates to mechanism and how it might be manipulated to achieve even higher values of Tc. Optics has been shown to be a powerful technique in this effort and we are world experts. A second important recent development in condensed matter physics has been the discovery of topological materials which has introduced new concepts and indeed new ways of thinking about semimetals. It has led to the rapid development of our understanding of the importance of topology in providing electronic systems with entirely new functionalities. This holds the potential for transformative impact on opto-electronic devices, on spintronics, magnetic memories, solar cells, water filtration, on quantum computing and more generally on communications. New materials in this area are discovered at a rapid rate partly because of advances in theory. Powerful new numerical techniques allows us to accurately predict electronic structure and implied properties. We propose to calculate select properties of new topological semimetals including Weyl and Dirac materials as they are discovered in the laboratory, with the aim of increasing understanding of what new and unique properties are possible. Already new Weyl fermions have been found in solid state systems that have no counterpart in high energy particle physics. So fundamental new physics is being discovered which could impact future technologies. The proposed research program will also provide solid training in advanced mathematical, numerical and computing techniques to graduate students, highly desirable and transferable skills to many other areas.