Micromagnetic Simulation of Spin-Wave Eigenmodes in Ferromagnetic Microstructures
Dipl. Phys. Markus Bolte (Universität Hamburg, Inst. f. Angewandte Physik)

Abstract:
In the presentation I will explain the basic principles of micromagnetic simulations and a few numerical integration techniques to speed up the computation. A modified simulation package was used to compute the spin-wave spectra of micrometer sized permalloy rectangles in remanence. Ultra-short field pulses of various spatial symmetries are used to excite distinct spin-wave eigenmodes. The frequencies as well as the symmetry of the mode patterns depend on the symmetry of the exciting field pulse and the magnetic ground state. We find transversal modes as well as longitudinal modes as observed experimentally. From the mode profiles an effective dispersion relation is deduced which resembles the dispersion relation for infinitely extended thin films.
In the last part of the talk the knowledge of the eigenmodes of ferromagnetic structures was exploited to excite a 16x32µm2 permalloy strucuture with one of its eigenfrequencies. The result was an enlargement of the mode to maximize the entropy in this excited system.