A LEED PROBE FOR SURFACE SPIN SYSTEMS*

Abstract: Information about the spin structure of a surface is contained in ditf LEED intensities via spin-orbit scattering or, in the case of fer-romagnets, exchange scattering. Such information, for example, can be exploited for determination of surface magnetic structure or for profiling surface barrier potentials. The influence of spin scattering on the measured LEED intensities can be enhanced by polarizing the incident electron beam. In the spin-polarized LEED system described here, the electron source is zero-electron-affinity Ga As + Cs- 0- Cs, illuminated by circularly polarized light. After pas-sage through a 90 ’ electrostatic deflector to convert the photoemitted elec-trons from longitudinal to transverse polarization, the beam passes a con-stant magnification lens before striking the sample at energies from 10-200 eV. Diffracted intensities are m ensured by a minicomputer-controlled Faraday cup. Data reduction, st(,rage, and display occur via dedicated link between the minicomputer and an iBM 370. A synchronous method for measuring the scattered polarization and preliminary results are discussed