Fermi Surface Cross-Sectional Images from Photoelectron Angular Distributions

最近的兴趣领域，如薄膜磁性和高 温度超导性强调了需要 费米表面的详细测量。该提案涉及 通过使用新开发的技术， 光电子能谱测定费米面。的 该技术通常适用于各种材料， 将提供散装和表面系统的信息。是 敏感的费米表面的结构在低的区域 对称性和研究可以在高温下进行 其中相变可能是重要的。 测量将使用一种新型的显示型电子 能量分析仪，将产生能量分辨二维 光电发射强度与发射角的图像。工作 将在路易斯安那州立大学先进微结构中心进行， 装置（CAMD）同步加速器光源。初步调查 将涉及贵金属，这是很好地理解，从以前的 研究，并将在以后扩展到金属与严重嵌套 费米面。这些材料中的一些经历磁相 费米表面的拓扑结构可以改变的过渡 这些实验将进一步支持理论 中求进工作总这些技术也将应用于高温 超导体的性质的带拦截 费米面将被研究。由于该方法样本量大， 在k空间的区域中，将对这些材料进行调查， 功能，并将提供快速概述电子 结构常规仪器将用于高- 适当时进行分辨率研究。这项工作将在 与劳伦斯利弗莫尔实验室的研究人员合作， 美国国家标准与技术研究所（National Institute of Standards and Technology） 高校 %%% 随着新型材料的开发， 表征其相关性质必须改进。这种需要 将在开发一种新的显示型电子 能量分析仪，以执行光电子能谱， 成像模式。测量依赖于同步辐射， 从感兴趣的材料的表面发射电子;这 辐射将由路易斯安那州立大学先进中心提供 微结构与器件（CAMD）储存环。通过成像 发射的方向，材料的详细性质 费米面是可以探索的。这提供的信息是 对材料行为的理论理解很有价值， 为材料加工的改进提供反馈。 最初，该方法将应用于金属系统， 其他技术也很好理解。该方法将得到完善 研究具有更复杂费米表面的材料， 通过强迫它们经历磁相变而改变， 将用于展示方法的灵活性。 最后，这种先进的仪器将应用于高 温度超导体作为超导电性的起源 铜酸盐氧化物仍然是难以捉摸的。该项目提供了新的 一种表征费米电子态的方法 表面，并将导致更好地了解基本的 电子特性由于测量依赖于最高的 优质材料，与劳伦斯大学的研究人员合作， 利弗莫尔实验室，国家标准研究所，并在 其他大学也将参与其中。

Recent interest in areas such as thin-film magnetics and high temperature superconductivity have underscored the need for detailed measurements of Fermi surfaces. This proposal addresses the problem by using a newly developed technique using photoelectron spectroscopy to determine Fermi surfaces. The technique is generally applicable to a wide range of materials and will provide information on both bulk and surface systems. It is sensitive to the structure of the Fermi surface in regions of low symmetry and studies can be performed at elevated temperatures where phase transitions may be important. Measurements will be made using a novel display-type electron energy analyzer that will produce energy resolved two dimensional images of photoemission intensity versus emission angle. The work will be conducted at the LSU Center for Advanced Microstructure and Devices (CAMD) synchrotron light source. The initial investigations will involve noble metals which are well-understood from previous studies and will later be extended to metals with heavily nested Fermi surfaces. Some of these materials undergo magnetic phase transitions where the topology of the Fermi surface can change substantially; such experiments will support further theoretical progress. These techniques will also be applied to high temperature superconductors where the nature of the bands intercepting the Fermi surface will be investigated. Since the method samples large regions of k-space, these materials will be surveyed for unexpected features and will provide the rapid overviews of electronic structure. Conventional instrumentation will be used for high- resolution studies when appropriate. The work will be done in collaboration with researchers at Lawrence Livermore Laboratory, the National Institute of Standards and Technology at other universities. %%% As new classes of materials are developed, techniques for characterizing their relevant properties must improve. This need will be addressed in the development of a new display-type electron energy analyzer, to perform photoelectron spectroscopy in an imaging mode. The measurements rely on synchrotron radiation to eject electrons from surfaces of the material of interest; this radiation will be provided by the LSU Center for Advanced Microstructure and Devices (CAMD) storage ring. By imaging the directions of the emission, the detailed nature of the material's Fermi surface can be explored. This provides information that is valuable for a theoretical understanding of material behavior and gives feedback for improvements in materials processing. Initially, the method will be applied to metallic systems that are well understood by other techniques. The approach will refined to study materials with more complicated Fermi surfaces that can be altered by coercing them to undergo magnetic phase transitions and will be used to demonstrate the flexibility of the methodology. Finally, this advanced instrumentation will be applied to high temperature superconductors as the origin of superconductivity in the cuprate oxides remains elusive. The project provides a new method for characterizing the electronic states at the Fermi surface and will result in an improved understanding of fundamental electronic properties. As the measurements rely on the highest quality materials, collaboration with researchers at the Lawrence Livermore Laboratory, the National Institute of Standards, and at other universities will be undertaken.//