Development of a Spin Polarized Inverse Photoemission Spectrometer

自旋偏振逆光电发射光谱仪的研制

• 批准号: 9407933
• 负责人: Peter Dowben
• 金额: $ 8.07万
• 依托单位: University of Nebraska-Lincoln
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1994
• 资助国家: 美国
• 起止时间: 1994-07-01 至 1995-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9407933&HistoricalAwards=false
• 关键词: Development; Spin; Polarized; Inverse; Photoemission

This work is concerned with building a new facility to study the spin-polarized unoccupied bands of ferromagnetic thin films and surfaces and Mott-Hubbard insulators. This facility will permit, in conjunction with existing spin polarized photoemission facilities, to identify the exchange splitting of large local moment systems where spin mixing rather than exchange splitting collapse occurs. As with ferromagnetic systems, we also plan, in the case of systems exhibiting Mott-Hubbard transitions, to identify the upper Hubbard band in systems where the Hubbard bands exhibit ferromagnetic (as opposed to antiferromagnetic) ordering. By building this facility, the characterization of not only the occupied band structure (the occupied density of states) but the unoccupied band structure (the unoccupied density of states) is possible. This proposal is based upon existing expertise of five research groups in photoemission, spin- polarized photoemission, inverse photoemission, spin-polarized electron sources, and magnetism. %%% Photoemission, has been the spectroscopy of choice in characterizing electronic structure. The use of polarized light in angle-resolved photoemission studies has made the identification of electronic bands through symmetry selection rules possible, greatly enhancing the technique. These techniques probe the occupied part of the band structure: the valence bands of semiconductors or occupied states of metals and condensed matter systems. More recently, inverse photoemission studies have found a unique role for exploring the conduction band of semiconductors or the unoccupied states of metals and condensed matter systems. Spin-resolved photoemission and spin-resolved inverse photoemission have greatly enhanced the study of electronic structure; particularly in the case of systems with spin-ordered bands, such as ferromagnetic systems. We propose to complement our existing facilities with spin resolved inverse photoemission capability in order to chara cterize both occupied and unoccupied parts of the band structure. This combination of facilities will substantially enhance the ability to investigate magnetic thin films and surfaces and nonmetal to metal transitions. It is this combination of techniques at a single center which would be unmatched by any other facility in the world.

这项工作涉及建立一个新的设施，以研究铁磁性薄膜和表面的自旋偏振无占用的带和莫特 - 哈伯德绝缘子。该设施将允许与现有的自旋偏振光发射设施结合使用，以确定旋转混合而不是交换分裂崩溃的大型当地矩系统的交换分裂。与铁磁系统一样，我们还计划在表现出Mott-Hubbard跃迁的系统的情况下，以识别哈伯德频段表现出铁磁性（与抗fiferromagnetic）订购的系统中的上哈伯德频带。通过构建此设施，不仅可以表征被占用的带状结构（状态的占据密度），而且可以进行空置的带状结构（状态的未占用密度）。该建议基于五个研究小组的现有专业知识，在光发射，旋转光发射，逆光发射，自旋极化电子源和磁性方面。 %% %%光发射一直是表征电子结构的选择光谱。在角度分辨光发射研究中使用极化光已通过对称选择规则可以识别电子带，从而大大增强了技术。这些技术探测了频带结构的占据部分：半导体的价带或金属和冷凝物质系统的占用状态。最近，逆光发射研究发现了探索半导体的传导带或金属和冷凝物质系统的无占用状态的独特作用。自旋分辨光发射和自旋分辨的逆光发射大大增强了电子结构的研究。特别是对于具有自旋级带的系统，例如铁磁系统。我们建议通过旋转的逆光发射能力来补充我们现有的设施，以使频带结构的占据和无人居住的部分构成。设施的这种组合将大大提高研究磁性薄膜和表面以及非金属转换的能力。正是在一个中心的这种技术组合，世界上任何其他设施都将无与伦比。