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MA: Fachverband Magnetismus
MA 30: Spin-Dynamics / Spin-Torque III
MA 30.11: Vortrag
Donnerstag, 26. März 2009, 12:45–13:00, HSZ 04
Coupling of spin-wave eigenmodes in small magnetic ring structures — •Björn Obry1, Helmut Schultheiß1, Christian Sandweg1, Sebastian J. Hermsdörfer1, Sebastian Schäfer1, Vasyl Tiberkevich2, Britta Leven1, Andrei N. Slavin2, and Burkard Hillebrands1 — 1FB Physik and Forschungszentrum OPTIMAS, TU Kaiserslautern, 67663 Kaiserslautern, Germany — 2Department of Physics, Oakland University, Rochester, MI, USA
Understanding the coupling of spin-wave eigenmodes in small magnetic structures is of great importance for future applications of those structures in technical devices. Measurements with time- and space-resolved Brillouin light scattering microscopy were performed on permalloy rings placed on top of a coplanar waveguide in order to excite spin waves by the Oersted field of a microwave current. The rings under investigation have outer diameters between 1 and 3 µm, ring widths of 100 to 400 nm and a thickness of 15 nm. Being magnetized in the onion state the rings reveal a direct coupling of spin-wave modes excited near the poles of the ring with modes confined to the equatorial region via three-magnon scattering processes. Excitation of spin waves confined only to the pole regions will result in the appearance of a spin-wave signal at the equators, if the frequency ratio between modes in the equatorial and pole regions is 2:1, fulfilling energy conservation for three-magnon scattering. The coupling turns out to be tunable by the external magnetic field and can be shown for rings of various diameters and widths. Financial support by the DFG (SPP1133) is acknowledged.