Parallels between a system of coupled magnetic vortices and a ferromagnetic/nonmagnetic (FM/NM) multilayer system

The coupling of interacting magnetic nanodisks with vortex configuration has interesting consequences, and has possible applications in the transport and processing of information. We show, through micromagnetic simulation and the use of Thiele's equation, that the coupling of magnetic vortices and the phenomenon of spin pumping in FM/NM multilayers, although arising from different physical mechanisms, show significant parallels. We study the variation of the effective damping (α_eff) of the system formed by a string of nanodisks with magnetic vortex structure, and Gilbert damping constant α₁, interacting with another disk with Gilbert constant α₂ (α₂⩾α₁). The result of varying the number of disks in the string is analogous to the observed variation of effective damping as a function of FM layer thickness, in FM/NM multilayers. The variation of the value of α₂ is analogous to the ability of the NM layer to act as a spin sink, for different NM materials. We also obtain that the effective damping goes through a maximum as a function of the value of damping α₂; an analogous effect is present in experiments with FM/NM systems, when the thickness of the NM layer is varied.