Magnetic vortex gyration mediated by point-contact position*

Abstract

Micromagnetic simulation is employed to study the gyration motion of magnetic vortices in distinct permalloy nanodisks driven by a spin-polarized current. The critical current density for magnetic vortex gyration, eigenfrequency, trajectory, velocity and the time for a magnetic vortex to obtain the steady gyration are analyzed. Simulation results reveal that the magnetic vortices in larger and thinner nanodisks can achieve a lower-frequency gyration at a lower current density in a shorter time. However, the magnetic vortices in thicker nanodisks need a higher current density and longer time to attain steady gyration but with a higher eigenfrequency. We also find that the point-contact position exerts different influences on these parameters in different nanodisks, which contributes to the control of the magnetic vortex gyration. The conclusions of this paper can serve as a theoretical basis for designing nano-oscillators and microwave frequency modulators.

Micromagnetic study of magnetization reversal in inhomogeneous permanent magnets

“…[18] Instead, micromagnetic simulation provides an important way to reveal the magnetization dynamics in permanent magnets. [23][24][25] Up to date, micromagnetic simulations [26][27][28][29] have been widely used to study the magnetization phenomena on the intermediate scale between the quantum mechanical scale of individual atoms and the macroscale, such as the dynamic response of a micromagnetic system and the characterization of 3D magnetization distribution. [9,30] By employing large-scale micromagnetic simulations, the effects of grain size, [31] grain shape, [32] and grain boundary phase [33] on the coercivity of Nd-Fe-B permanent magnets were well investigated.…”