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

EAGER：SUPER：超导聚氢化物微观特性的实验表征；

• 批准号: 2132692
• 负责人: Shanti Deemyad
• 金额: $ 30万
• 依托单位: University of Utah
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-08-01 至 2025-07-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2132692&HistoricalAwards=false
• 关键词: EAGER; SUPER; Experimental; characterization; microscopic

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.

非技术描述：超导体完美地传输电力并排除磁场。超导体的卓越特性可以实现无损能量传输、磁悬浮设备的设计，并且是量子计算技术的关键。基于超导的技术依赖于发现在接近环境条件下工作的超导材料，这仍然是一个尚未解决的挑战。最近在富氢材料中发现了室温超导性，尽管是在极高的压力下。为了找到临界压力较低的室温超导体，需要具有预测能力的精确理论模型。然而，在实验上，暖超导状态在微观层面上的表征还不够充分，无法完全约束理论模型。该项目旨在借助新型光谱工具来解决这个问题，这些工具克服了高压下材料表征的固有困难。通过维持实验和理论之间的反馈循环，该项目将开发一个强大的框架来理解热超导性，以及一个具有直接技术应用预测能力的模型。该项目将培养具有实验和理论能力、具有跳出框框思维、探索新领域、引领下一代科学发现的前沿科学学生。技术描述：在极端压力下发现了聚氢化物中的温暖超导状态，这种状态仅在金刚石砧室中达到。大多数热超导状态的表征，例如磁化率和电阻率，都是为了检测超导性的开始而进行的。然而，这些测量不足以完全约束理论模型，并对理论对达到环境条件超导体的预测能力设定限制。约束理论模型的两个重要参数是超导能隙和超导转变附近的电子-声子耦合常数。然而，与环境压力超导体不同，金刚石砧室的几何形状和尺寸限制了适用的表征方法的类型。在该项目中，使用PI实验室先进的光谱方法，包括电子拉曼光谱和超快泵浦探针测量，目的是系统地表征聚氢化物超导体的超导状态并确定基本参数。并行理论分析和建模将允许接近聚氢化物超导性的真实微观模型，并在理论指导下发现环境条件超导材料。该项目将促进对温超导及其技术应用的实验和理论理解。学生接受尖端实验和理论技术的培训，并参与一项研究计划，为他们提供科学方法以及理论与观察之间的联系的丰富经验。该奖项反映了 NSF 的法定使命，并通过评估被认为值得支持基金会的智力价值和更广泛的影响审查标准。

项目成果

Structure and pressure dependence of the Fermi surface of lithium

锂费米面的结构和压力依赖性

• DOI: 10.1103/physrevb.106.l041112
• 发表时间: 2022-07-18
• 期刊: Physical Review B
• 影响因子: 3.7
• 作者: Tushar Bhowmick;S. Elatresh;A. Grockowiak;W. Coniglio;M. T. Hossain;E. Nicol;S. Tozer;S. Bonev;S. Deemyad
• 通讯作者: S. Deemyad