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

9501419古德里奇在这个项目中，朗道量子振荡的测量是在高温超导体的正常和超导混合状态。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它超导体的大块单晶。 研究的物理包括费米表面拓扑结构，有效质量，和散射率的电子在正常状态;相互作用的正常电子与磁通涡旋的混合状态;和行为 的 超导 性能 的 高 在强朗道量子化的正常态背景下的温度超导材料。正常状态下的费米面测量将给出这些材料中超导机制理论的关键参数值。混合态的结果将导致电子-电子和电子-磁通量涡旋相互作用的一个很大的改进的描述。 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。 目前的工作是针对获得有关这种机制在各种高温超导体的信息，通过测量的基本性质的电子参与超导性，在超导和正常（电阻）的条件。通过使用强磁场和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，这些信息可以用来定量地评估和测试这些理论。 这些测量是利用路易斯安那州立大学的国家高磁场实验室和橡树岭国家实验室的专门设施进行的。 ***

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. ***