| 題目 | Chaos Control of Spin-Wave Excitation |
| 講師 | Prof. Hartmut Benner (Darmstadt工科大学) |
| 日時 | 9 月 28 日（木）16:00 - 17:30 |
| 場所 | コラボレーション室（コラボレーションセンター３階） |
| 要旨 | Suppression and control of
chaos has recently received increased attention. We report on ferromagnetic
resonance experiments in yttrium irun garnet (YIG) spheres probing regular
and irregular auto-oscillations above the first-order Suhl instability.
Different techniques have been applied to suppress the observed chaotic
oscillations and to stabilize specific regular
ones: (i) We demonstrate the suppression of chaos by fast parametric modulation and show that the increase of modulation amplitude actually results in an effective variation of the modulated control parameter. (ii) The OGY method which requires precise knowledge of the unstable periodic orbit to be stabilized makes use of the internal system dynamics in a rather sophisticated way. Application to spin-wave chaos is only possible in terms of modified schemes, e.g. occasional proportional feedback, which has been implemented by means of a fast electronic devices. (iii) Time-delayed feedback methods, which are of particular interest for fast experimental systems, may be considered as an efficient compromise combining simplicity of application with low controlling power. Although these methods have been successfully applied in many real experiments, a theoretical understanding was supplied only very recently and allows to optimize the efficiency of control. |
| Key words | Chaos control, Spin-wave, YIG, Ferromagnetic resonance |
| 世話人 | 山嵜比登志 (内線7822） |