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

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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. ***