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MA: Fachverband Magnetismus

MA 13: Surface Magnetism

MA 13.2: Vortrag

Dienstag, 26. Februar 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 J_i,j S_i^† S_j . It’s exchange integrals J_i,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 S_i^†  M_i,j S_j with the 3×3 matrices  M_i,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  M_i,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)