Development of a Novel Helium Beam Scattering Multi- technique/detection Facility to Study Surface Lattice and Spin-wave Dynamics, and Spin-resolved Electronic Structure

9512564 El-Batanouny 这项研究将开发一个多功能的多技术/多检测系统，与新开发的双原子束（DAB）单色仪用于表面研究。该仪器将能够测量固体表面的磁性和自旋相关的电子结构，以及相关的动力学性质。DAB单色器可以产生基态氦原子或自旋极化亚稳氦原子的单能束。探测系统的核心是一个小型化的角度分辨混合探测器，它可以提供色散原子速度分析以及亚稳态原子的检测。要进行的磁性测量涉及确定表面电子自旋极化的长程有序性和表面自旋波（磁振子）的动力学性质。双原子束操作模式允许区分表面磁振子和表面声子，因为自旋极化原子束耦合到表面磁振子和声子，而基态原子束仅耦合到表面声子。该技术适用于研究具有高度相关电子系统的材料，如高温铜酸盐超导体和其他过渡金属化合物。 这个新颖而独特的系统的实现将开辟一个新的研究领域，涉及表面电子自旋态及其动力学的性质，这仍然是现有技术无法实现的。所提出的系统是简单的，创新的，用户友好的，它预计将有更广泛的用途，商业化生产的潜力。 ***

9512564 El-Batanouny This research will develop a versatile multi-technique/multi- detection system to be used in conjunction with a newly developed dual atomic beam (DAB) monochromator to be used for surface studies. The instrument will be capable of measuring the magnetic and spin-dependent electronic structure of solid surfaces, as well as the related dynamical properties. The DAB monochromator can generate a mono-energetic beam of either ground-state helium atoms or spin-polarized metastable helium atoms. The heart of the detection system is a miniaturized angle-resolved hybrid detector which can provide dispersive atom-velocity analysis as well as detection of metastable atoms. Magnetic measurements to be performed involve determining the long-range order of surface electron spin polarization and the dynamical properties of surface spin waves (magnons). The dual atomic beam mode of operation permits to distinguish between surface magnons and surface phonons, as the spin-polarized atom beam couples to both surface magnons and phonons while the ground state atom beam couples only to surface phonons. The technique is suitable for the study of materials with highly correlated electron systems, such as high temperature cuprate superconductors and other transition metal compounds. %%% The implementation of this novel and unique system will open a new area of research involving the properties of surface electron-spin states and their dynamics, which remains inaccessible to existing techniques. The proposed system is simple, innovative, and user-friendly enough that it is expected to have a wider use, with the potential for commercial production. ***