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We report on the first successful double-scattering low-energy electron diffraction experiment, which clearly reveals spin-polarization effects. Polarization and intensity of the specular beam from W(001) have been measured as functions of the azimuthal angle of incidence ("rotation diagrams"). The agreement of the data with their theoretical counterparts is quite satisfactory. High polarization sensitivity and detector efficiency in the present experiment demonstrate the feasibility of a new type of spin-polarization detector.

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For cubic (001), ( 110) and ( 111) surface systems with in-plane or perpendicular magnetization, valence-band photoemission along the surface normal is studied analytically by evaluating electric dipole transition matrix elements between half-space initial and final states of the appropriate double-group symmetry. Explicit expressions are obtained for the spin-polarization vector of the photoelectrons, and the spin-averaged intensity and its change upon reversal of the magnetization direction, i.e. magnetic dichroism, for circularly and linearly polarized incident light. These results firstly elucidate the origin of spin polarization and dichroism in terms of an interplay between spin-orbit coupling and exchange, and secondly provide a systematic overview of possible effects. In particular, we predict new types of magnetic linear dichroism for s-polarized light in the case of magnetization perpendicular to surfaces with a twofold rotation axis and in the case of in-plane magnetization of fcc (111) or hcp (0001) surfaces.

A review is given of elastic spin-polarised low-energy electron diffraction (SPLEED) from crystalline surfaces. For the two relevant spin-dependent interaction mechanisms, spin-orbit coupling, and exchange, dynamical theories are presented with emphasis on symmetry principles, potential models and multiple scattering formalisms. Brief accounts of computational aspects and experimental apparatus (polarised-electron source, spin detectors) are followed by a survey and discussion of experimental and theoretical results for non-magnetic and magnetic surfaces. Finally, the impact of SPLEED on electron emission methods is pointed out, and the prospects of SPLEED as a powerful tool for surface analysis are assessed.