Investigation of optically-driven supercondcutors using pump-probe Raman scattering

使用泵浦探针拉曼散射研究光驱动超导体

• 批准号: 2210126
• 负责人: Dmitry Reznik
• 金额: $ 40.62万
• 依托单位: University of Colorado at Boulder
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-08-01 至 2025-07-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2210126&HistoricalAwards=false
• 关键词: Investigation; optically; driven; supercondcutors; using

Non-Technical Abstract Superconductivity is characterized by a complete loss of electrical resistance. It is a quantum state that arises out of strong interactions of electronic charges and orbitals, magnetism, and vibrations of atoms. The specific mechanisms in many materials are puzzling to scientists. This project takes advantage of a recently developed experimental technique, pump-probe Raman spectroscopy, to investigate superconductivity in so-called transient states. These occur right after a very short laser pulse hits the material and either kicks some electrons out of their orbits or induces large amplitude vibrations of the atoms. The material can briefly go into a different transient state, e.g., a superconductor will lose superconductivity, or the opposite can happen – superconductivity may arise in a material that does not exhibit it under normal circumstances. Time-resolved Raman scattering creates a movie of how these states develop and how they come back to the original state. The main idea behind this project is to make such movies of superconductors to reveal otherwise hidden quantum processes. This knowledge is used to test ideas about mechanisms of superconductivity and helps to harness superconductors for practical applications. The work is carried out at the ultrafast laser spectroscopy laboratory at the University of Colorado-Boulder built with the funds provided earlier by the National Science Foundation. The project contributes to the education and training of graduate and undergraduate students.Technical AbstractThis project focuses on groundbreaking measurements of superconductors shortly after absorption of an ultrashort laser pulse. The purpose is to experimentally investigate still enigmatic mechanisms of equilibrium superconductivity in copper oxides as well as the general phenomenon of light-induced nonequilibrium superconductivity. In the experiments, the investigated sample is driven out of equilibrium by a short laser pulse, and Raman scattering from another time-delayed pulse will probe its relaxation. These experiments track time-evolution of phonons, electronic temperature, and the superconducting gap as the system thermalizes. This novel approach elucidates energy flows, transient timescales, and heating in optically-driven superconductivity recently reported in intercalated C60 and some copper oxides. Nonlinear phononics and Josephson current-based mechanisms suggested as explanations of this phenomenon are tested. Advances in this area will ultimately underlie development of new materials and devices involving optical control of superconductivity. The work is carried out at the ultrafast laser spectroscopy laboratory at the University of Colorado-Boulder built with the funds provided previously by National Science Foundation. The project contributes to the education and training of graduate and undergraduate 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.

非技术摘要超导性的特征是电阻的完全丧失。它是一种量子态，产生于电子电荷和轨道，磁性和原子振动的强烈相互作用。许多材料中的具体机制令科学家感到困惑。本计画利用最新发展之抽运-探测拉曼光谱技术，来研究所谓暂态的超导性。这些发生在非常短的激光脉冲击中材料之后，要么将一些电子踢出轨道，要么引起原子的大幅振动。材料可以短暂地进入不同的瞬态，例如，超导体将失去超导性，或者相反的情况也可能发生--超导性可能出现在正常情况下不表现出超导性的材料中。时间分辨的拉曼散射产生了这些状态如何发展以及它们如何回到原始状态的电影。这个项目背后的主要想法是制作这样的超导体电影，以揭示隐藏的量子过程。这些知识用于测试有关超导机制的想法，并有助于将超导体用于实际应用。这项工作是在科罗拉多大学博尔德分校的超快激光光谱实验室进行的，该实验室由美国国家科学基金会早些时候提供的资金建造。该项目有助于研究生和本科生的教育和培训。技术摘要本项目的重点是突破性的测量超导体吸收后不久的超短激光脉冲。目的是实验研究仍然是谜一样的铜氧化物的平衡超导机制以及光致非平衡超导的一般现象。在实验中，所研究的样品被一个短的激光脉冲驱动离开平衡，并且来自另一个时间延迟脉冲的拉曼散射将探测其弛豫。这些实验跟踪声子的时间演化，电子温度和超导间隙作为系统热化。这种新的方法阐明了能量流，瞬态时间尺度，和加热的光驱动超导最近报道的嵌入C60和一些铜氧化物。非线性声子和约瑟夫森电流为基础的机制，建议解释这种现象进行了测试。这一领域的进展将最终成为涉及超导性光学控制的新材料和器件开发的基础。这项工作是在科罗拉多大学博尔德分校的超快激光光谱实验室进行的，该实验室由美国国家科学基金会提供资金。该项目有助于研究生和本科生的教育和培训。该奖项反映了NSF的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。