Berlin 2012 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 34: Magnetization / Demagnetization Dynamics III

MA 34.12: Vortrag

Mittwoch, 28. März 2012, 18:00–18:15, H 1012

Micromagnetic simulation of spin wave mediated synchronization between two pointcontact spin torque nano-oscillators — •Thomas Kendziorczyk and Tilmann Kuhn — Institut für Festkörpertheorie, Universität Münster, Wilhelm-Klemm-Str. 10, 48149 Münster

It has been predicted theoretically and observed experimentally that a direct current traversing a magnetic multilayer exerts a spin torque on the magnetic system which can compensate the natural damping and lead to magnetic autooscillations in the GHz range. Due to the easy frequency tunability and the narrow linewidth of the spin torque nano-oscillators (STNOs) this effect has great potential for the construction of nanosized microwave generators. The main problem which has to be solved for future applications is the low output power of a single STNO. In order to construct larger arrays of STNOs a good knowledge about the coupling mechanism between them is indispensable. We have performed micromagnetic simulations based on the Landau-Lifshitz equation including dipolar and exchange interactions with a supplementary spin torque transfer term. We will show that the STNOs can synchronize mutually due to exchange of spin waves and oscillate coherently with the same frequency. The phase difference and spatial coherence of the STNOs depend on the distance between them and differences in their size. These results can be explained by means of a simple model of two coupled differential equations describing nonlinear autooscillators.