Ultrafast imaging of incoherent rotation magnetic switching with experimental and numerical micromagnetic dynamics

The magnetic switching dynamics of a thin-film microstructured Permalloy element were directly observed undergoing incoherent rotation reversal processes. Experimental spatiotemporally and vectorially resolved micromagnetic data show qualitative agreement with numerically simulated micromagnetic data for the nonequilibrium states during reversal. The application of a longitudinal reversal field launches rotations in both clockwise and counterclockwise directions, governed by magnetostatic effects, at different locations within a shaped sample. Reversal proceeds by fast initial selection into these rotation directions, immediately leading to vortex formation throughout the sample, and is followed by slower expulsion of the vortices in the transverse-to-field direction through local coherent rotation. Apparent transient damping, magnetization vector length averages, and spatial frequency representations support energy transfer concepts for the reversal process.