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MA: Fachverband Magnetismus

MA 63: Poster II (Surface Magnetism/ Magnetic Imaging/ Topological Insulators/ Spin Structures and Magnetic Phase Transitions/ Graphene/ Magnetic Thin Films/ Magnetic Semiconductors/ Magnetic Half-metals and Oxides/ Spin-dependent Transport/ Spin Excitations and Spin Torque/ Spin Injection and Spin Currents in Heterostructures/ Spintronics/ Magnetic Storage and Applications)

MA 63.84: Poster

Freitag, 18. März 2011, 11:00–14:00, P2

Higher-order corrections to the magnon dispersion in the Heisenberg model — •Julian Hüser, Thomas Kendziorczyk, and Tilmann Kuhn — Institut für Festkörpertheorie, Universität Münster, Wilhelm-Klemm-Str. 10, 48149 Münster

It is well known that in thin magnetic films the magnon energy spectrum exhibits a minimum at nonzero wavevectors where Bose-Einstein condensation can take place. The main mechanism which leads to this minimum is a competition between exchange and dipole-dipole interactions. Most fundamental work is based on the Heisenberg model in the spirit of the 1/S-approximation which is able to explain this complex dispersion relation. Because of the nonlinearity of the Holstein-Primakoff transformation higher-order terms react on the linear terms and thus modify the dispersion relation. However this correction has been neglected so far and barely investigations were made to confirm the validity of the 1/S-approximation. The present work provides an analysis of the higher-order terms and shows in which cases the corrections are negligible or not.