Spin-flip exchange scattering of low-energy electrons in ferromagnetic iron

We present a theory of spin-flip exchange scattering of low-energy electrons, directed at the ferromagnetic transition metals, with application to Fe. The model used employs a tight-binding description of the paramagnetic spd bands. Ferromagnetic exchange splitting of the bands is achieved by including on-site Coulomb repulsion between electrons in 3d orbitals, which is treated in a mean-field approximation. The low-energy electron interacts with the metal electrons via the Coulomb interaction, and the magnetic excitations in the metal are treated within the random-phase approximation. Both spin waves and Stoner excitations contribute to the energy loss of the low-energy electron. We show that the relative importance of these two loss mechanisms is influenced very importantly by the degree of localization of the 3d orbital. We also present results based on the use of accurate wave functions. These show that spin-wave loss peaks should be prominent features in spin-polarized electron energy-loss spectra. [S0163-1829(98)03745-X].