Damped Free Oscillation of Magnetization in Ni-Fe Thin Films

Citation

Suezawa, Yoshitaka (1976) Damped Free Oscillation of Magnetization in Ni-Fe Thin Films. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/MD0Y-D860. https://resolver.caltech.edu/CaltechTHESIS:02232017-094033612

Abstract

Damped free oscillations of the magnetization have been clearly observed at the completion of 180° flux reversal along both the easy and the hard axis in Ni-Fe thin films. The flux component perpendicular to the applied pulse field was observed using a single turn pickup loop around the film. The frequency of the oscillation was studied as a function of applied pulse field and compared with the results obtained by ferromagnetic resonance. The frequency of the damped free oscillation agreed quite well with that obtained by resonance when the frequency was measured after the oscillation had damped to small amplitude. The damping constant obtained from the decay of the oscillation agreed quite well with that obtained from the half-power line-width of the resonance curve.

The Landau-Lifshitz equation proposed for the coherent rotation, using the value of the damping constant obtained by resonance, could describe the initial part of the magnetization reversal and the damped free oscillation in the films with low angular dispersion. Agreement between the experimental and the calculated transverse flux change for the entire waveform could not be obtained by using the value of damping constant obtained by resonance. The agreement was better at both higher applied field or lower anisotropy dispersion. The effect of eddy currents was negligible on the flux reversal but appeared as a slight increase of the damping constant obtained by resonance experiment.

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