Berlin 2008 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 30: Electron Theory

MA 30.5: Vortrag

Donnerstag, 28. Februar 2008, 15:30–15:45, H 1028

Wannier-function approach to spin-wave excitations in transition metals — •Ersoy Sasioglu, Arno Schindlmayr, Christoph Friedrich, and Stefan Blügel — Institut für Festkörperforschung, Forschungszentrum Jülich, 52425 Jülich, Germany

We develop a computational scheme based on many-body perturbation theory to study excitation spectra of magnetic materials from first principles using Wannier functions. The main quantity of interest is the spin-spin correlation function (or dynamical 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 collective spin-wave excitations 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 all-electron full-potential linearized augmented plane-wave (FLAPW) method. As a first step, we calculate the dynamical spin susceptibility of the non-interacting Kohn-Sham electrons and the matrix elements of the Coulomb potential in the Wannier basis. The obtained values for the latter are in good agreement with previous calculations. This work was funded in part by the EU’s Sixth Framework Programme through the Nanoquanta Network of Excellence (NMP-4-CT-2004-500198).