EAGER: SUPER: Experimental characterization of microscopic properties of superconducting polyhydrides; towards a realistic theoretical framework for warm superconductivity

非技术描述：超导体完美地传输电力并排除磁场。超导体的显著特性允许无损能量传输，设计磁悬浮设备，是量子计算技术的关键。基于超导体的技术依赖于发现在接近环境的条件下工作的超导材料，这仍然是一个悬而未决的挑战。最近在富氢材料中发现了室温超导电性，尽管是在极高的压力下。为了寻找具有较低临界压力的室温超导体，需要一个具有预测功率的精确理论模型。然而，在实验上，热超导态在微观水平上的特征不足以完全约束理论模型。该项目旨在借助新的光谱工具来解决这一问题，这些工具可以克服在高压下表征材料的固有困难。通过保持实验和理论之间的反馈回路，该项目将导致开发一个强大的框架来理解热超导，并为直接技术应用开发一个具有预测能力的模型。该项目将培养在实验和理论方面都有能力的尖端科学学生，具有跳出框框思考的远见，探索新的前沿，并领导下一代科学发现。技术描述：在极端压力下，已经发现了多氢化合物中的温超导态，这种状态只在金刚石顶压室中才能达到。对热超导状态的大多数表征，如磁化率和电阻率，都是为了探测超导的开始。然而，这些测量不足以完全约束理论模型，并限制了理论对达到环境条件超导体的预测能力。约束理论模型的两个基本参数是超导带隙和超导转变附近的电声子耦合常数。然而，与常压超导体不同的是，钻石砧座单元的几何形状和大小限制了适用的表征方法的类型。在这个项目中，使用了包括电子拉曼光谱和PI实验室先进的超快泵浦-探测测量在内的光谱方法，目的是系统地表征聚氢化物超导体的超导态并确定基本参数。并行的理论分析和建模将允许接近现实的多氢超导微观模型，并以理论为指导发现环境条件下的超导材料。该项目将促进对热超导及其在技术上的应用的实验和理论理解。学生接受尖端实验和理论技术方面的培训，并参加一个研究项目，该项目为他们提供丰富的科学方法经验以及理论与观测之间的联系。该奖项反映了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 DESCRIPTION: Superconductors perfectly transmit electricity and exclude magnetic fields. The remarkable properties of superconductors allow lossless energy transmission, design of magnetically levitating devices, and are key to quantum computation technology. Superconductor-based technology relies on discovery of superconducting materials that operate at conditions close to ambient, which remains an unsolved challenge. Superconductivity at room temperature was recently discovered in hydrogen-rich materials albeit at extremely high pressures. To find room-temperature superconductors with lower critical pressure, an accurate theoretical model with predictive power is required. However, experimentally, the warm superconducting state is insufficiently characterized at microscopic level to fully constrain the theoretical models. This project aims to tackle this issue with the aid of novel spectroscopic tools that overcome inherent difficulties of characterization of materials at high pressures. By maintaining a feedback loop between experiment and theory, the project will lead to the development of a robust framework for understanding warm superconductivity and a model with predictive power for direct technological applications. The project will train students in cutting-edge science who are competent in both experiment and theory, have vision to think out of the box to explore the new frontiers and lead the next generation of scientific discoveries. TECHNICAL DESCRIPTION: Warm superconducting states in polyhydrides have been discovered under extreme pressures, reached exclusively in diamond anvil cells. The majority of characterizations of warm superconducting states, like magnetic susceptibility and electrical resistivity, are being made with the goal of detecting the onset of the superconductivity. These measurements are however insufficient to fully constrain the theoretical models and set limitations on the predictive power of the theories towards reaching an ambient-conditions superconductor. Two essential parameters for constraining the theoretical models are the superconducting gap and the electron-phonon coupling constant near the superconducting transition. Unlike ambient pressure superconductors, however, the geometry and size of a diamond anvil cell, limits the types of applicable characterization methods. In this project, spectroscopic methods including electronic Raman spectroscopy and ultrafast pump-probe measurements advanced in the PI's laboratory are used with the goal of systematic characterization of the superconducting states of polyhydride superconductors and determination of the fundamental parameters. Parallel theoretical analysis and modeling will allow approaching a realistic microscopic model for superconductivity of polyhydrides and theory-guided discovery of ambient-conditions superconducting materials. This project will advance experimental and theoretical understanding of warm superconductivity and its application in technology. Students receive training in cutting-edge experimental and theoretical techniques and participate in a research program that provides them with a rich experience in scientific method and connection between theory and observations.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.