Micromagnetics of magnetisation reversal mechanism in Permalloy chain-of-sphere structure with magnetic vortices

Magnetisation reversal mechanism in a chain of closely spaced Permalloy nanospheres is presented using 3D micromagnetic simulation. While smaller spheres (d ∼ 20 nm) containing single domain reverses via domain switching mechanism, the larger sphere (d ∼ 50 nm) possessing magnetic vortices changes the orientation through vortex creation and annihilation (VCA) mechanism. The effect of total number of spheres (comprising the chain structure) and incidence angle of externally applied field on the VCA mechanism is explained in detail. The variation in coercivity, remanence, exchange energy and vortex parameters are discussed for the Permalloy chain-of-sphere system with uniform sphere size.