Dynamics of vortex core switching in ferromagnetic nanodisks

Abstract

Dynamics of magnetic vortex core switching in nanometer-scale permalloy disk, having a single vortex ground state, was investigated by micromagnetic modeling. When an in-plane magnetic field pulse with an appropriate strength and duration is applied to the vortex structure, additional two vortices, i.e., a circular-and an anti-vortex, are created near the original vortex core. Sequentially, the vortex-antivortex pair annihilates. A spin wave is created at the annihilation point and propagated through the entire element; the relaxed state for the system is the single vortex state with a switched vortex core.

Current-induced magnetic vortex core switching in a Permalloy nanodisk

“…Based on micromagnetic simulations, a faster route to achieve core reversal has been proposed recently. 11,12 In this case, which does not use the gyrotropic resonance, the reversal is induced by a suitably shaped unipolar in-plane magnetic field pulse only a few picoseconds long. The required amplitude of the field pulse is larger ͓approximately 70 mT ͑Ref.…”

Controlled vortex core switching in a magnetic nanodisk by a rotating field

“…The azimuthal mode is caused by the influence of the in-plane field and the symmetrical one by the effective out-of plane field B ⊥ . Due to the continuous pumping the system goes to the nonlinear regime: the amplitude of the azimuthal mode increases and there appears an out-of-plane dip nearby the vortex, similar to the vortex structure distortion by the in-plane field pulse [24,25,26] or an AC oscillating field [27]; this dip is shown on the right panel of Fig. 2 by the dark gray color and it is surrounded by the white isosurface.…”

Polarity reversal of a magnetic vortex core by a unipolar, nonresonant in-plane pulsed magnetic field

“…In these two cases, reversal was observed for rf excitation close to the translational-mode eigenfrequency. However, theoretical work [4][5][6] and experiments 7,8 suggest that nonresonant pulsed excitations also promote core reversal.…”