Elastic exchange scattering amplitude studied using magnetic EXAFS

Magnetic or spin-dependent extended x-ray-absorption fine-structure (EXAFS) studies have been performed at the K edges of pure Co and Ni and at the L-1,L-2,L-3 edges of Gd metal. Using a two-step model for the absorption process and introducing an additive-exchange contribution to the complex Coulomb scattering amplitude and the electron mean free path, an ansatz for the description of the magnetic EXAFS is derived. A parametrization of these quantities is proposed for an extraction of the spin-dependent values from the experimental data. The results for the elastic exchange scattering cross section in the energy range of 100-600 eV are in excellent agreement with theoretical predictions from a Born-Ockhur approximation. The inelastic exchange scattering effects are found to be negligible.