Theory of the spin dynamics of bulk Fe and ultrathin Fe(100) films

We present theoretical studies of the spin dynamics of bulk Fe and of ultrathin Fe(1 0 0) films, within an empirical tight binding description of the one electron energies. We use a Slater-Koster parameterization of the bulk paramagnetic energy bands, and apply these to the film. Ferromagnetic ground states are generated by introducing intra-atomic Coulomb repulsion within the d shell of each atom. The intra-atomic Coulomb matrix elements are expressed in terms of three Racah parameters, whose values are chosen to describe the ferromagnetism of the bulk. We calculate the transverse dynamic spin susceptibility of both the bulk and a film with a (1 0 0) surface, within the random phase approximation (RPA). Such an approach describes the spin wave excitations of these systems, and their Stoner spectrum as well. (C) 1998 Elsevier Science B.V. All rights reserved.