High Precision Landau Quantum Oscillation Measurements in the Normal and Mixed States of High-Temperature Superconductors

高温超导体正常状态和混合状态下的高精度朗道量子振荡测量

• 批准号: 9501419
• 负责人: Roy Goodrich
• 金额: $ 26万
• 依托单位: Louisiana State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1995
• 资助国家: 美国
• 起止时间: 1995-06-01 至 1999-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9501419&HistoricalAwards=false
• 关键词: Precision; Landau; Quantum; Oscillation; Measurements

9501419 Goodrich In this project, measurements of Landau quantum oscillations are made on high temperature superconductors in both the normal and the superconducting mixed states. Both epitaxial films of yttrium barium copper oxide and bismuth strontium rare-earth copper oxide, and bulk single crystals of other superconductors are studied. The physics investigated includes Fermi surface topologies, effective masses, and scattering rates for electrons in the normal state; the interaction of normal electrons with flux vortices in the mixed state; and the behavior of superconducting properties of high temperature superconducting materials in the presence of a strongly Landau- quantized normal-state background. The Fermi surface measurements in the normal state will give values for parameters that are crucial to theories of the mechanism of superconductivity in these materials. The mixed state results will lead to a much improved description of electron-electron and electron-flux vortex interactions. %%% One of the problems limiting the development of materials that exhibit truly high-temperature superconductivity (above the temperature of liquid nitrogen, -196 deg C) is that the basic mechanism responsible for high-temperature superconductivity remains unknown. The present work is directed toward gaining information about this mechanism in a variety of high-temperature superconductors by measuring fundamental properties of the electrons that participate in superconductivity, in both the super-conducting and normal (resistive) condition. By using strong magnetic fields and measuring the quantized magnetism of the electrons, precise values are obtained for parameters that are crucial to theories of superconductivity. This information can then be used to evaluate and test quantitatively these theories. The measurements are made using specialized facilities at the National High Magnetic Field Labo ratory, at Louisiana State University, and at Oak Ridge National Laboratory. ***

9501419 Goodrich 在这个项目中，朗道量子振荡的测量是在常态和超导混合态的高温超导体上进行的。研究了钇钡铜氧化物和铋锶稀土铜氧化物的外延薄膜以及其他超导体的块状单晶。 研究的物理学包括费米表面拓扑、有效质量和正常状态下电子的散射率；混合状态下普通电子与通量涡旋的相互作用； 以及在强朗道量子化的正常态背景下高温超导材料的超导特性的行为。正常状态下的费米表面测量将给出对这些材料的超导机制理论至关重要的参数值。混合态结果将大大改进对电子-电子和电子-通量涡旋相互作用的描述。 %%% 限制开发真正具有高温超导性（高于液氮温度，-196 摄氏度）的材料的问题之一是高温超导性的基本机制仍然未知。 目前的工作旨在通过测量超导和正常（电阻）条件下参与超导性的电子的基本特性，获得有关各种高温超导体中这种机制的信息。通过使用强磁场并测量电子的量子化磁性，可以获得对超导理论至关重要的参数的精确值。然后可以使用该信息来定量评估和测试这些理论。 这些测量是使用国家高磁场实验室、路易斯安那州立大学和橡树岭国家实验室的专门设施进行的。 ***