Investigation of quantum materials using tunable pump-probe Raman scattering

使用可调谐泵浦探针拉曼散射研究量子材料

• 批准号: 1709946
• 负责人: Dmitry Reznik
• 金额: $ 48.33万
• 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: 2017
• 资助国家: 美国
• 起止时间: 2017-08-01 至 2022-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1709946&HistoricalAwards=false
• 关键词: Investigation; quantum; materials; using; tunable

Non-Technical Abstract: In quantum materials such as superconductors and topological insulators quantum physics underlies most important properties. Unraveling the puzzles posed by these materials is one of the main scientific challenges of the 21st century, with direct relevance to new generations of electronic, energy, and medical technologies. This project is devoted to observing how these materials evolve in time after being hit by a short laser pulse. Using a new experimental technique, pump-probe Raman spectroscopy, the researchers make movies of how quantum materials evolve in time taking frames every 0.00000000000001 sec. Light travels a fraction of a millimeter during these time intervals, so very fast processes can be detected in slow motion. A weak laser pulse may kick some electrons out of their orbits. These will hit atoms and other electrons revealing interactions between electrons and the atomic lattice. If the laser pulse is strong, the material can briefly go into a different state, e.g. a superconductor will lose superconductivity. Observing how it comes back to the original state reveals otherwise hidden mechanisms. This knowledge is used to test fundamental theories and helps to harness quantum materials for practical applications in electronics, photonics, and energy. The work is carried out at the ultrafast laser spectroscopy laboratory at the University of Colorado (CU)-Boulder built with the funds provided previously by the National Science Foundation (NSF). It is be a part of a Ph.D. thesis of two graduate students and contributes to undergraduate education.Technical Abstract: This project focuses on groundbreaking measurements of materials where quantum physics underlies most important physical properties. The general goal is to understand how these materials behave away from thermal equilibrium: The investigated sample is driven out of equilibrium by a short laser pulse, and another time-delayed laser pulse probes its relaxation by serving as the excitation laser for Raman spectroscopy. The work is carried out at the new ultrafast laser spectroscopy laboratory at the University of Colorado (CU)-Boulder built with the funds provided previously by National Science Foundation (NSF). The laser system at the heart of this laboratory is one of the most advanced of its kind in the world. It is utilized for pump-probe angle-resolved photoemission spectroscopy and pump-probe Raman spectroscopy. This project represents the Raman component of this effort. All Raman active excitations are tracked during relaxation. These include phonons, magnons, and some electronic excitations across gaps of up to 5eV. Raman scattering can directly probe the energies, lifetimes, and population of excited states (e.g. phonon occupation numbers). The time-resolved Raman scattering measurements are on charge density wave (CDW) systems, different types of superconductors, Mott insulators, and novel spin-orbit materials. They display diverse and often still enigmatic physical phenomena of great interest and the principal investigator already investigated them by other related techniques. It is a part of a Ph.D. thesis of two graduate students and contributes to undergraduate education.

非技术摘要：在超导体和拓扑绝缘体等量子材料中，量子物理是最重要的性质。解开这些材料带来的谜团是21世纪的主要科学挑战之一，与新一代电子、能源和医疗技术直接相关。该项目致力于观察这些材料在受到短激光脉冲撞击后的时间演化过程。使用一种名为泵浦探测拉曼光谱的新实验技术，研究人员制作了量子材料如何随时间演变的电影，每隔0.00000000000001秒拍摄一帧。在这些时间间隔内，光的传播速度只有一毫米的几分之一，因此可以在慢动作中检测到非常快的过程。微弱的激光脉冲可能会把一些电子踢出轨道。它们将撞击原子和其他电子，揭示电子与原子晶格之间的相互作用。如果激光脉冲很强，材料可能会短暂地进入不同的状态，例如，超导体将失去超导电性。观察它是如何恢复到原始状态的，揭示了其他隐藏的机制。这些知识被用来测试基本理论，并有助于利用量子材料在电子、光子学和能源方面的实际应用。这项工作是在科罗拉多大学博尔德分校的超快激光光谱学实验室进行的，该实验室以前是由国家科学基金会(NSF)提供资金建造的。这是两名研究生博士论文的一部分，对本科教育有贡献。技术摘要：这个项目专注于材料的突破性测量，量子物理是最重要的物理性质的基础。总的目标是了解这些材料如何脱离热平衡：被研究的样品被短的激光脉冲驱离平衡，而另一个延时的激光脉冲作为拉曼光谱的激发激光来探测它的弛豫。这项工作是在科罗拉多大学博尔德分校新的超快激光光谱学实验室进行的，该实验室以前是由国家科学基金会(NSF)提供资金建造的。这个实验室的核心激光系统是世界上最先进的激光系统之一。它被用于泵浦-探测角度分辨光电子能谱和泵浦-探测拉曼光谱。该项目代表了这项工作的拉曼部分。在弛豫过程中跟踪了所有的拉曼活性激发。其中包括声子、磁子和高达5 eV能隙的一些电子激发。拉曼散射可以直接探测激发态的能量、寿命和布居(如声子占据数)。在电荷密度波(CDW)系统、不同类型的超导体、Mott绝缘体和新型自旋轨道材料上进行了时间分辨拉曼散射测量。它们展示了各种令人感兴趣的神秘物理现象，首席研究员已经用其他相关技术对它们进行了研究。它是两名研究生博士论文的一部分，对本科教育做出了贡献。

项目成果

Electron-phonon coupling in the undoped cuprate YBa2Cu3O6 estimated from Raman and optical conductivity spectra

• DOI: 10.1103/physrevb.98.121104
• 发表时间: 2018-09-11
• 期刊: PHYSICAL REVIEW B
• 影响因子: 3.7
• 作者: Farina, D.;De Filippis, G.;Cataudella, V
• 通讯作者: Cataudella, V

Relaxation timescales and electron-phonon coupling in optically pumped YBa2Cu3O6+x revealed by time-resolved Raman scattering

• DOI: 10.1103/physrevb.104.l180505
• 发表时间: 2020-10
• 期刊: Physical Review B
• 影响因子: 3.7
• 作者: N. Pellatz;S. Roy;J-W. Lee;J. Schad;H. Kandel;N. Arndt;C. Eom;A. Kemper;D. Reznik

Ultrafast magnetic dynamics in insulating YBa2Cu3O6.1 revealed by time resolved two-magnon Raman scattering

• DOI: 10.1038/s41467-020-16275-9
• 发表时间: 2020-05-21
• 期刊: NATURE COMMUNICATIONS
• 影响因子: 16.6
• 作者: Yang, Jhih-An;Pellatz, Nicholas;Reznik, Dmitry
• 通讯作者: Reznik, Dmitry