Direct correlation of reversal rate dynamics to domain configurations in micron-sized permalloy elements

The distribution of states upon the removal of applied magnetic field in an array of 7.5×7.5μm2 permalloy square elements, as observed by transmission electron microscopy in Lorentz mode, shows a predominance of two states: the vortex state and the seven-domain state. The distributional dependence of these two states on the rate of change of the reversal field is established. Micromagnetic simulations suggest that vortex nucleation and the subsequent domain-wall propagation are the two primary mechanisms for magnetization reversal. The kinetics of the two pathways is examined in a manner that conforms to the observed distribution of states.