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MA: Fachverband Magnetismus

MA 20: Micromagnetism / Computational Magnetics

MA 20.1: Vortrag

Mittwoch, 24. März 2010, 17:00–17:15, H22

Transmission and reflection of spin waves in the presence of Néel walls. — •Sebastian Macke and Dagmar Goll — Max-Planck-Institut für Metallforschung, Heisenbergstr. 3, 70569 Stuttgart

Within the framework of the continuum theory of micromagnetism the interaction of spin waves with domain walls is presented.

For a thin stripe a coupled differential equation system based on the linearization of the Landau-Lifshitz-Gilbert equation is derived including exchange interaction, crystal anisotropy and demagnetization field. The ground state of the stripe is a homogeneous magnetization state on both sides of the stripe separated by a Néel-type domain wall. On one side of the stripe monochromatic spin waves with well-defined frequency and orientation are excited. Then the reflected and transmitted fractions of the spin wave are analyzed. For wavelengths larger than the wall width we observe a reflection of the waves while for smaller wavelengths the spin waves transmit by 100%. The phase of the spin wave can shift on a wide range. A resonance effect inside the domain wall can occur for special wave vectors. It will be shown that especially the demagnetizing field plays a fundamental role. The accuracy of the method is tested for special cases using micromagnetic finite element simulations. Different materials are analyzed dependent on the thickness of the stripe and the direction of the spin wave.