Dependence of spatial coherence of coherent suppression of magnetization precession upon aspect ratio in Ni 81Fe 19 microdots

Abstract

Coherent suppression of magnetization dynamics in circular microdots of Ni81Fe19 has been observed by time-resolved scanning Kerr effect microscopy. The applied pulsed field rose sharply, stimulating precession, and then exhibited an oscillatory behavior. For certain values of the static magnetic field the precession was suppressed at the point at which the magnetization lay in the sample plane. Time resolved images confirmed that coherent suppression had occurred at the center of the element, but nonuniformity was observed at the edges of the element, which became greater with decreasing aspect ratio. The nonuniform magnetization dynamics result from the dephasing of confined spin wave modes, suggesting that a more involved pulse shaping scheme may be required to coherently suppress the full mode spectrum.