Spin Dynamics in Permalloy Disks with Vortex Structure
Abstract
Micron sized ferromagnetic permalloy disks exhibiting a ferromagnetic vortex structure are excited by a magnetic field pulse. The fast rise time pulse field is generated by an optically triggered electrical pulse in a lithographically fabricated microcoil. Experiments were performed for a series of different sample dimensions. The excitation is imaged using time resolved magneto-optic polar Kerr microscopy in a stroboscopic experiment. We present the spatially resolved magnetic maps at different delay times, stitched together to form a magnetic movie. The dynamical excitations are composed of symmetric and non-sysmmetric parts which can not be separated at first glance. However, in a detailed analysis up to five Eigen-modes can be extracted from the data and can be visualized in the Fourier transform of the magnetic movie. The symmetric excitations can be accounted for in a simple model based purely on dipolar interactions. The model is supported by micromagnetic simulations and shows good quantitative agreement in the resonance frequencies for different modes. Furthermore, insight can be gained into the energy dissipation of the system from the same data.
- Publication:
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APS March Meeting Abstracts
- Pub Date:
- March 2004
- Bibcode:
- 2004APS..MARB23012B