Dresden 2009 – scientific programme
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O: Fachverband Oberflächenphysik
O 67: Ab-initio approaches to excitations in condensed matter III
O 67.2: Talk
Friday, March 27, 2009, 11:30–11:45, SCH 251
Spin-wave excitations in itinerant ferromagnets from many-body perturbation theory — •Ersoy Sasioglu1, Arno Schindlmayr2, Christoph Friedrich1, and Stefan Blügel1 — 1Institut für Festkörperforschung and Institute for Advanced Simulation, Forschungszentrum Jülich, 52425 Jülich, Germany — 2Department Physik, Universität Paderborn, 33095 Paderborn, Germany
To study excitation spectra of magnetic materials from first principles we have developed a computational scheme based on many-body perturbation theory. The main quantity of interest is the dynamical transverse spin susceptibility, from which magnetic excitations, including single-particle spin-flip Stoner excitations and collective spin-wave modes as well as their lifetimes, can be obtained. In order to describe spin waves we include appropriate vertex corrections in the form of a multiple-scattering T-matrix, which describes the coupling of electrons and holes with different spin. To reduce the numerical cost for the calculation of the four-point T-matrix we exploit a transformation to maximally localized Wannier functions that takes advantage of the short spatial range of electronic correlation in the partially filled d or f orbitals of magnetic materials. Our implementation is based on the full-potential linearized augmented plane-wave (FLAPW) method. As an illustration, we present spin-wave spectra and dispersions for the elementary ferromagnets Fe, Co and Ni calculated with our scheme. The results are in good agreement with available experimental data.