Berlin 2008 – scientific programme
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MA: Fachverband Magnetismus
MA 13: Surface Magnetism
MA 13.2: Talk
Tuesday, February 26, 2008, 10:45–11:00, EB 301
Ab initio calculation of symmetric and antisymmetric exchange parameters — •Marcus Heide, Gustav Bihlmayer, and Stefan Blügel — Institut für Festk"orperforschung (IFF), Forschungszentrum Jülich
A simple approximation to the energy of a spin configuration is the classical Heisenberg model E=∑i,j Ji,j Si† Sj . It’s exchange integrals Ji,j are dominated by non-relativistic effects. Staying within a bilinear approximation but accounting for spin-orbit coupling effects, the model can be generalized by E= ∑i,j Si† Mi,j Sj with the 3×3 matrices Mi,j [1]. This matrices contain terms describing the symmetric and antisymmetric (Dzyaloshinskii-Moriya) exchange as well as the magnetocrystalline anisotropy.
In this talk, we focus on thin magnetic surface films of hexagonal geometry and estimate the matrices Mi,j from first principles. Thereby, we employ spin-spiral calculations in order to obtain the exchange terms. The resulting ground states are discussed within our model ansatz.
[1] T. Moriya, Phys. Rev. 120, 91 (1960)