SGER: In-Situ Measurements of Small Angle Neutron Scattering and AC Magnetic Susceptibility of Vortex Matter

SGER：涡旋物质小角中子散射和交流磁化率的原位测量

• 批准号: 0075838
• 负责人: Xinsheng Ling
• 金额: $ 5.39万
• 依托单位: Brown University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-03-01 至 2001-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0075838&HistoricalAwards=false
• 关键词: SGER; Situ; Measurements; Small; Angle

0075838LingThis is a Small Grant for Exploratory Research (SGER) to a young faculty member at Brown University. He will study vortex phases in the regime where the random potential caused by defects in the material competes with vortex-vortex interactions and thermal fluctuations giving rise to the "peak effect" in type-II superconductors. The vortex physics in this regime will be studied in a single crystal of Nb using a coil wound directly on the sample to measure the vortex dynamics and simultaneously using Small Angle Neutron Scattering (SANS) to measure the neutron diffraction pattern of the vortex array. This experiment is highly exploratory since the neutron diffraction signal from a vortex array is very weak in the peak effect regime. If successful, this project will generate experimental results that will reveal the direct correlation between the microscopic properties of the vortex lattice and the macroscopic properties of a type-II superconductor in a magnetic field. The question of vortex pinning-depinning is one of technological importance and thus this research could have a high payoff. A graduate student will participate in this research, thereby gaining the experience of working at a National Facility (the Center for High-Resolution Neutron Scattering at NIST) as well as working on a high-risk, high payoff project. This should prepare the student for future work in academia, industry, or government.%%%The capability to carry an electric current without dissipation makes superconductors useful in many applications such as MRI magnets, power transmission, etc. Most technologically useful superconducting materials allow a strong magnetic field to penetrate into the material to form quantized magnetic vortices. In an ideal, defect-free type-II superconductor these vortex lines will move and cause dissipation under the driving force of a current. Fortunately, imperfections, defects, and impurities, in the atomic lattice can pin the vortex lines, allowing a superconducting wire to carry a large lossless current. Therefore a good understanding of the pining of the vortex lattice by random impurities is beneficial to many applications. This Small Grant for Exploratory Research (SGER) will fund a project that will use a neutron beam to study the microscopic structure of the vortex lattice that gives rise to what is known as the anomalous peak effect. This effect allows a superconductor to carry more current at a higher magnetic field and temperature. If successful this project will reveal the direct correlation between the microscopic structure of the vortex lattice and the macroscopic properties of a type-II superconductor in a magnetic field, and thus help scientists make better superconductors. The graduate student participating in this project will have the opportunity to work at a National Facility (the Center for High-Resolution Neutron Scattering at NIST) with researches from around the country. This should prepare the student for future work in academia, industry, or government.***

这是给布朗大学一位年轻教员的探索性研究(SGER)小额资助。他将研究涡旋相，在这种情况下，材料中缺陷引起的随机势与涡旋-涡旋相互作用和热涨落竞争，从而在第二类超导体中产生“峰值效应”。在这种情况下，将在Nb单晶中研究涡旋物理，使用直接缠绕在样品上的线圈来测量涡旋动力学，同时使用小角中子散射(SANS)来测量涡旋阵列的中子衍射图。由于涡旋阵列的中子衍射信号在峰值效应区非常微弱，因此本实验具有很强的探索性。如果成功，这个项目将产生实验结果，揭示涡旋晶格的微观性质与磁场中第二类超导体的宏观性质之间的直接关联。涡旋钉扎-去钉扎问题是技术上的重要问题之一，因此这项研究可能会有很高的回报。一名研究生将参与这项研究，从而获得在国家设施(NIST高分辨率中子散射中心)工作的经验，以及参与一个高风险、高回报的项目。这将为学生将来在学术界、工业界或政府部门的工作做好准备。%无耗散载流的能力使超导体在许多应用中都很有用，如核磁共振磁体、电力传输等。大多数技术有用的超导材料允许强大的磁场渗透到材料中，形成量化的磁涡流。在理想的、无缺陷的II型超导体中，这些涡旋线将在电流的驱动力下移动并引起耗散。幸运的是，原子晶格中的缺陷、缺陷和杂质可以钉住涡旋线，使超导导线能够携带大量无损电流。因此，很好地理解随机杂质对涡旋晶格的尖峰作用，对于许多应用都是有益的。这笔小额的探索性研究补助金(SGER)将资助一个项目，该项目将使用中子束来研究涡旋晶格的微观结构，这种结构会产生所谓的反常峰值效应。这种效应允许超导体在较高的磁场和温度下携带更多的电流。如果该项目成功，将揭示涡旋晶格的微观结构与磁场中第二类超导体的宏观性质之间的直接关联，从而帮助科学家制造更好的超导体。参与这个项目的研究生将有机会在国家设施(NIST的高分辨率中子散射中心)工作，从事来自全国各地的研究。这应该为学生将来在学术界、工业界或政府工作做好准备。*