Quantitative structural determination using spin-polarized low-energy electron diffraction rotation curves: W(110)

Abstract

Spin-polarized low-energy electron diffraction (LEED) rotation curves measured with 30 to 80 eV electrons scattered from a W(110) surface have been analysed with calculations using a relativistic multiple scattering theory, where quantitative reliability factors ( R-factors) have been used to find the best fit between theory and experiment. The Zanazzi–Jona R-factor was used for intensity data, and the mean-squared deviation between theory and experiment was used for the spin-polarization data. The variance of the R-factors for rotation curves has been derived, and varies as E −1/4 (where E is the scattering energy). This was used to estimate parameter uncertainties. The surface layer relaxation of W(110) was found to be −2.2±1.0% of the bulk layer spacing, in agreement with recent current–voltage LEED studies. These results illustrate that quantitative structural studies using low scattering energies may be performed with spin-polarized LEED rotation curves. This technique should be well suited to studies of magnetic ultrathin films, where magnetic-exchange scattering becomes more predominant at low scattering energies.