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MA: Fachverband Magnetismus

MA 52: Poster II - Magnetic Heusler compounds, Magnetic shape memory alloys, Thin Films, Micro-/Nano-structured magnetic materials, Graphene, Spins in organics, Magnetic imaging, Surface Magnetism, Spin excitations/Torque, Spincaloric transport

MA 52.30: Poster

Freitag, 30. März 2012, 11:00–14:00, Poster A

Magnonic modes in rectangular antidot lattices — •Jelena Panke, Benjamin Lenk, Nils Abeling, and Markus Münzenberg — I. Physikalisches Institut, Georg-August-Universität Göttingen

On the way towards spin-wave logic devices an understanding of mechanisms for the manipulation and guiding of spin waves is of crucial importance. Femtosecond laser pulses are used to optically excite (pump) and subsequently measure (probe) magnetization dynamics on timescales as long as nanoseconds. Two-dimensional arrays of antidots in a ferromagnetic film provide a periodic “potential” to the excited spin waves and induce drastic changes in the magnetization dynamics.

In the spin wave spectra of rectangular CoFeB antidot lattices different modes are observed which are influenced by the variation of material parameters (filling fraction, antidot diameter, lattice parameter). We focus on these Bloch-like modes and investigate the spin-wave population for different directions of the external field. By applying the external field along the long or short axis a_1,2 of the rectangular lattice a magnonic mode appears with a wave vector k=π/a_1,2 at the boundary of the first Brillouin zone for each respective direction. Therefore it is possible to tune the Bloch modes only by rotating the external field. Furthermore, band structure calculations are used to investigate the changed dispersion on the patterned media as compared to the continuous film. The periodic lattice structure induces band gaps at the zone boundary that are also sensitive to the field direction and can explain the prefered population of the magnonic modes.