This abstract was not submitted electronically.
[O5.02] Novel Electron Spin Analyzers and Their Applications
D.P. Pappas (Virginia Commonwealth University)
This abstract was not submitted electronically.
[O5.03] Optics for Polarization-Resolved Soft X-Ray Magneto-Optic Spectroscopies
Jeffrey Kortright (Lawrence Berkeley National Laboratory)
Polarization-active optical elements based on multilayer interference structures extend magneto-optic (MO) techniques common in the IR/visible/UV ranges into the 50 - 1000 eV soft x-ray range. These optics-based techniques complement other soft x-ray MO techniques which rely on the inherent polarization of synchrotron radiation. Working near core resonances makes these techniques element-specific, enabling study of the magnetism of individual elements in multicomponent samples, and can lead to larger MO responses than comparable measurements in the near-visible range. Linear polarizers result from periodic multilayers with periods adjusted to position the reflectance peak at 45 degrees (the x-ray Brewster angle). In addition to providing basic polarization measurement capabilities, linear polarizers extend Faraday and Kerr rotation techniques utilizing linear incident polarization into the soft x-ray. Tunable linear polarizers yield the spectroscopic behavior of these effects and element-resolved hysteresis loops. Multilayer phase retarders result from transmission through free-standing structures, and below roughly 150 eV have been used as near-quarter-wave plates in magnetic circular dichroism (MCD) measurements in photoemission. At higher photon energies in the soft x-ray, large MCD effects at transition and rare earth metal core levels can result in resonant phase retarders. These phase retarders can be used in conjunction with various soft x-ray microscopy schemes to yield element-resolved magnetic images with sub-micron resolution. This talk will introduce the principles and operation of the optics, and results of their early application in soft x-ray magneto-optical measurements.
[O5.04] Atomic Structure of Magnetic Materials via EXAFS and Its Variants
Vincent Harris (Naval Research Laboratory)
This abstract was not submitted electronically.
[O5.05] A framework for the qualitative analysis of magnetic dichroism in angle-resolved photoemission
D. Venus (McMaster University)
Magnetic dichroism experiments can provide detailed, quantitative information about magnetic films and nanostructures, particularly if one has access to synchrotron radiation with variable light polarization, spin analysis, and sophisticated first-principles photoemission calculations. However, the technique is much more widely accessible, and its use should grow rapidly when it is realized that it is not only for the specialist. Existing photoemission intensity experiments are easily adapted to make some magnetic dichroism experiments possible with linearly polarized light or laboratory sources, and straightforward methods of qualitative analysis already yield important information. Since magnetic dichroism arises due the interplay of the spin-orbit and exchange interactions in a magnetic material, magnetic dichroism in angle-resolved photoemission is a state-specific spectroscopy that allows the study of their combined influence on the electronic structure. In core-level photoemission the exchange interaction is a perturbation of the core states, and qualitative models based on atomic orbitals allow an evaluation of the internal splitting of the core multiplets. In valence band photoemission, the spin-orbit interaction is a perturbation of the band states, and qualitative models based on single-group band calculations allow an evaluation of band hybridization effects important to the magnetocrystalline anisotropy. In both cases, the photoelectron final state influences the measured dichroism through geometrical effects that encode structural information that is not readily accessible by qualitative analysis. The talk will be illustrated by experimental examples, including recent applications to valence band studies with VUV light.