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.

本工作是关于建立一个新的设备来研究自旋极化的铁磁薄膜和表面的空带和Mott-Hubbard绝缘体。该设施将允许，与现有的自旋极化光电发射设施，以确定交换分裂的大型本地时刻系统的自旋混合，而不是交换分裂崩溃发生。与铁磁系统，我们也计划，在系统表现出莫特-哈伯德过渡的情况下，以确定在系统中的哈伯德带表现出铁磁（而不是反铁磁）有序的上哈伯德带。通过构建该设备，不仅可以表征占据能带结构（占据态密度），还可以表征未占据能带结构（未占据态密度）。这个建议是基于现有的专业知识的五个研究小组在光电发射，自旋极化光电发射，逆光电发射，自旋极化电子源，和磁性。 %光电发射，一直是表征电子结构的光谱学的选择。在角分辨光电子能谱研究中使用偏振光使得通过对称性选择规则识别电子能带成为可能，极大地增强了该技术。这些技术探测能带结构的占据部分：半导体的价带或金属和凝聚态系统的占据态。最近，逆光电发射研究发现了探索半导体导带或金属和凝聚态系统的未占据态的独特作用。自旋分辨光电子能谱和自旋分辨逆光电子能谱极大地促进了电子结构的研究，特别是在具有自旋有序带的系统，如铁磁系统的情况下。我们建议补充我们现有的设备与自旋分辨逆光电发射能力，以chara cancelling占用和未占用的部分的能带结构。这种设备的组合将大大提高研究磁性薄膜和表面以及非金属到金属过渡的能力。这是一个单一中心的技术组合，这将是世界上任何其他设施无法比拟的。