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MA: Fachverband Magnetismus
MA 31: Magnetization Dynamics III
MA 31.3: Talk
Wednesday, March 16, 2011, 11:30–11:45, HSZ 403
Nonlinear magnon scattering in nano-sized Permalloy elements — •Henning Ulrichs1, Vladislav E. Demidov1, Sergej O. Demokritov1, and Sergei Urazhdin2 — 1Institut für angewandte Physik, Universität Münster, Correnstraße 2-4, 48149 Münster, Germany — 2Department of Physics, West Virginia University, Morgantown, WV 26506, USA
In this talk we will report about nonlinear magnetization dynamics in sub-micron-sized elliptical Permalloy dots. The dynamics was excited using intense microwave pulses and studied by means of micro-focus Brillouin light scattering spectroscopy. In the linear regime, one predominantly observes excitation of the fundamental eigenmode of the dot, which resembles the FMR mode in such a confined geometry. At higher pulse powers a secondary, low-frequency mode is excited in addition to the fundamental mode. This process nucleates at the center of the dot, where the amplitude of the fundamental mode shows a maximum. Our explanation assumes a scattering of magnons of the fundamental mode into the lowest frequency state. This process is reminiscent of the initial phase in the formation of magnon Bose-Einstein condensate observed in low-loss garnet films.